Individual Hardware Store Science Experiments

Hardware Store Science includes 28 individual modules addressing all of the topics typically covered in a high school physical science course. A teacher can select individual topics to use in their current courses or they can use the complete suite of experiments for a full two semester physical science course.

Organization of Science Experiment Modules.

Physical science is typically taught as a collection of disconnected topics, i.e. simple machines, potential and kinetic energy, chemical reaction, electric circuits, etc. However, there are some basic principles that underlie all of the physical science. These principles can effectively organize the various topics so they logically build upon each other. This is the approach that has been used to organize the topics in the suite of Hardware Store Science experiments. The teacher can use the experiments in any order that they find useful, but we believe there is an order that is most natural.

Physical science is organized around fundamental conservation principles: conservation of mass, conservation of energy, and conservation of momentum.

Conservation of mass is a key idea in chemical reactions, where the mass of the reactants equals the mass of the products although the reactant and product molecules are different.
Conservation of energy is the key principle behind a projectile where kinetic energy is converted into potential energy. Also, the 1^st law of thermodynamics is conservation of energy.
Conservation of linear momentum is Newton’s 2^nd law, i.e. F=ma. A more precise statement of Newton’s 2^nd law is the rate of change of momentum equals the sum of all forces, where for an object with constant mass Newton 2^nd law simplifies to F=ma..

Although these conservation principles are often not clearly covered in most high school physical science textbooks (these conservation principles are often reserved for an AP Physics course), we believe they are extremely useful in designing the organization of a general physical science course.

Section A, B, C and D in the curriculum are concerned with mechanics and are organized around the three conservation principles described above. Sections E and F are concerned with chemistry, starting with properties of gases, then introducing chemical reactions and finally including phase changes like melting. Basic electricity is introduced in Section G that includes the behavior of simple electrical components like resistors and capacitor, followed by experiments on more complex devices like electromagnets and motors. Finally, in Section H the basic principles of optics are introduced. The traditional way to teach a general physical science course is to start with the physics of mechanical world (i.e. Sections A through D) and then progress through chemistry (Sections E and F), electricity (Section G) and finally optics (Section H). Hardware Store Science materials have been written so the various sections can be rearranged to meet the needs of different instructors.

The 30 experiments in Section A through G are under development. A number of the experimental modules are complete, but others are under development. A complete list is provided in order to show that when completed, the Hardware Store Science modules will cover all of the topics in a general physical science course.

[accordion clicktoclose=”true”] [accordion-item title=”A. Mechanical Equilibrium and Conservation of Energy”]

The first six modules deal with Mechanical Equilibrium and Conservation of Energy. There is a natural flow of ideas in these six experiment which allows the experiments to build upon one another, starting with the simplest idea of levers introduced in Exp. 1. Each new experimental module introduces additional ideas, while reinforcing previous content. The key principles of Mechanical Equilibrium and provide a framework for both the physical science concepts introduced in this course and the idea that energy is interconverted between various forms but is always conserved.

This first set of 4 lessons and accompanying engineering challenge have been designed to introduce students to the law of conservation. Each lesson builds upon the lesson previous, providing re-enforcement of foundational material and introducing the next step with the scaffold of material. Each lesson is complete with student material, focus hardware store science investigation, teacher resources and answer key to practice problems, homework, and assessment material.

Exp. 1: Levers – It is a balancing act.

A lever is the most basic example of the simple machines. When the lever is balanced, the system is at mechanical equilibrium, and the work input on one end of the lever is equal to the work output done one the lever’s other end. This is observed through the downward force of the input work and the corresponding lifting effort of the output force.

In this initial experiment students construct a teeter-totter and then determine the basic principle of work and of how energy is conserved in a simple machine where there is almost no frictional losses.

Exp. 5: Pulleys.

The pulley is another simple machine. In an ideal pulley the work done in raising a weight on one side of the pulley is exactly equal to the work recovered in lowering a weight on the other side of the pulley. However, in the pulley experiment the students discover that the work input is slightly larger than the work output due to the frictional losses in the pulley. The Conservation of Energy principle is introduced where the change in potential energy due to raising/lower the weights plus the frictional loss in the pulley is zero.

Students develop a pulley system as a second example of a simple machine. The concept of work is analyzed, but now where there are frictional losses due to the pulley. The idea of conservation of energy as one of key principles of physics is discovered.

Exp. 6: Energy Storage – Stretching a Rubber Band.

When a rubber band is deformed by the addition of a weight, the change in potential energy as the weight lowers is stored in the rubber band. The Conservation of Energy principle now includes the energy stored in the rubber band that results from the elastic nature of the rubber band, and the mass of the object causing the rubber band to stretch.

Students determine how far a rubber band will stretch for a given weight, where the change in potential energy of the weight is stored in the rubber band. The effect of thickness of the rubber band (or multiple rubber bands) and the initial length of the rubber band is studied. The students discover the concepts of stress, strain and Young’s modulus

Exp. 7: Ball Launcher.

A plastic ball launcher powered by a rubber band is used to study how the trajectory of the ball depends the launch angle and how far the rubber band has been extended, where the students measure the ball’s trajectory using their cell phones. The Conservation of Energy principle is expanded to show how (i) the energy stored in a stretched rubber band is converted into kinetic energy upon launching of the plastic projectile (although some of the energy stored in the rubber band is lost to frictional processes in the launcher) and (ii) how kinetic energy is converted into potential energy and vice-a-versa as the ball moves through space.

In this experiments students construct a rubber band powered ping-pong ball launcher, where the launch angle and rubber band extension can be controlled. The flight of the ping-pong ball is recorded using a smart phone app, where the video can be slowed down for analysis of position as a function of time. Analyzing the data enables calculation of velocity, understanding of the interconversion between kinetic and potential energy during flight, and effect of air drag on the trajectory of the ball.

Engineering Challenge: Backyard Roller Coaster.

This project is the first of periodic engineering challenges that combines the first four investigations (Exp. 1-Levers, Exp. 2-Pulleys, Exp. 3-Energy Storage, Exp. 4-Projectile Motion). Students discover the interplay of work, forces, potential and kinetic energy, and the Law of Conservation. They investigate how these connect within the context of engineering and the work of engineers.

The five experiments above are all grounded on the principles of Mechanical Equilibrium and Conservation of Energy. The experiments build upon each starting with the simplest idea of levers introduced in Exp. 1. Each new experimental module introduces additional ideas, while reinforcing previous content. Mechanical Equilibrium and Conservation of Energy are the key principles that provide a framework for both the physical science concepts introduced in this course as well as a general principle in the world at large, where energy is interconverted between various forms but is always conserved.

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[accordion clicktoclose=”true”] [accordion-item title=”B. Friction and Conservation of Momentum”]

The second set of experiments expand upon the Conservation of Energy principle and Mechanical Equilibrium by introducing a more detailed analysis of both Fluid and Sliding Friction and Conservation of Linear Momentum in the form of Newton’s 2^nd Law. These experiments complete the exploration of the major concepts of linear motion and the forces that cause and effect linear motion.

Like the first set of 4 modules and accompanying engineering challenge, each lesson will build upon the lesson previous, providing re-enforcement of foundational material and introducing the next step with the scaffold of material. Each lesson will be complete with student material, focus hardware store science investigation, teacher resources and answer key to practice problems, homework, and assessment material.

Exp. 9: Sliding Friction.

In this experiment a tangential force is applied to a block and the movement of the sliding block is measured, where the concepts of static friction, dynamic friction, tangential force and normal force are explored.

Students construct an experimental device where they apply both tangential and normal forces to a block of wood sliding on a long panel. They record the displacement of the sliding block using cell phone video app and then determine the velocity. Students discover static friction, dynamic friction and how they depend upon the normal stress and the tangential stress. The effect of different surfaces and lubricants can be studied.

Exp. 10: Material Stiffness – Beam Bending.

Materials deform when subjected to a load. The key property is Young’s modulus, which will be explored by (i) revisiting the rubber band stretching in Exp. 3 and (ii) in a beam bending experiment, where the effect of material deformation is still consistent with Mechanical Equilibrium.

In this experiment students construct a beam bending apparatus where they measure the deflection of a beam as a function of the location and amount of an applied load. Using the data the students will be able to (i) compare their deflection results with the beam bending equations, (ii) examine the effect of beam cross-sectional area and (iii) use the experimentally determined beam deflection to determine the modulus of the material.

These four experiments complete the exploration of the major concepts of linear motion and the forces that cause and effect linear motion.

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[accordion clicktoclose=”true”] [accordion-item title=”C. Circular Motion, Centripetal Force and Torque”]

The first 9 experiments are concerned with linear motion, but circular motion is also important in numerous applications like satellites in earth orbit, vehicles turning corners, etc., where centripetal force is a natural consequence of circular motion.

Like previous lessons and accompanying engineering challenges, each lesson will build upon the lesson previous, providing re-enforcement of foundational material and introducing the next step with the scaffold of material. Each lesson will be complete with student material, focus hardware store science investigation, teacher resources and answer key to practice problems, homework, and assessment material.

Exp. 11: Circular Motion and Centripetal Force.

Using a rotating turntable the centripetal force is measured as a function of the angular velocity. The centripetal force resulting from radial acceleration during circular motion is an additional force in Newton’s 2^nd Law.

A large turntable made from wood and powered by a drill is constructed by student teams, where the centrifugal force is measured by observing the radial motion of a ball attached to a string that is mounted on the turntable. Students discover how the centripetal force depends upon the angular velocity of the turntable and the distance for the axis of rotation. The effect of ball diameter, string length, etc. on the centrifugal force measuring device will be studied.

Exp. 12: Torque and Gearing.

Just like a force causes a linear motion, torque causes an angular motion. This experiment has two components: First, it is discovered that torque is the result of a force applied through a lever arm. Second, it is shown that application of torque causes the rotation of a wheel, where the angular acceleration is proportional to the torque. A device is constructed by the students to measure the force required to turn a beam, where they then discover that a constant amount of torque (i.e. radius times the tangential force) is needed to produce a given angular motion. Students then explore the torque required to twist various objects, e.g. a rod or cylinder of different lengths, in order to discover/validate the engineering design equations for the various shapes.

A gear train is used to show how gears can either increase or decrease the rate of angular rotation. Just like the pulley system studied in Exp. 2 an ideal gear system (i.e. one without friction) will perfectly transfer the applied work between two gears; however, real gear systems have friction that reduce the effectiveness of the assembly. Students assemble a collection of gears in order to show how rotation speed can be increased or decreased by the use of either a single gear or a combination of gears. The students then learn how torque is transmitted through a gear or gear train, where they discover that frictional losses affect the amount of transmitted torque from that expected just from conservation of energy.

Exp. 13: Center-of-Gravity.

The lever experiment in Exp. 1 assumes that (i) there is no friction in the ‘knife’ edge upon which the lever is balanced and (ii) the ‘knife’ edge is very thin. The Center-of-Gravity experiment revisits this concept for the situation when the support is not thin. The basic principle of mechanical equilibrium still holds, but the methodology of determining when an object tips over is now more complicated.

A small wood frame is constructed and used to determine the center-of-gravity as a function of location of various weights using kitchen scales. Students discover that when the center-of-gravity is outside the base of the instrument the unit will tip over. The effect of weight location on the stability in various engineering applications can be explored.

Engineering Challenge: Turn Radius.

This project is the second engineering challenge and combines four of the previous investigations (Exp. 9-Sliding Friction, Exp. 11-Circular Motion, Exp. 12-Torque and Gearing, Exp. 13-Center of Mass). Students discover the interplay of the forces acting on automobiles as they navigate a turn. Students will look at frictional forces and center of mass characteristics associated with circular motion, and apply conservation laws. They investigate how these connect within the context of engineering and the work of engineers.

With the completion of Sections A, B and C, all of the necessary mechanics topics in a high school general physical science course have been covered. Student should have an understanding of the basic features of both linear and circular motion and forces required to cause those motions. There have also been two engineering challenge problems where student teams can combine the science principles that they have learned to construct and analyze a more complex situation that involves two or more concepts.

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[accordion clicktoclose=”true”] [accordion-item title=”D. Gas Behavior and Chemical Reaction”]

The next set of 4 experiments are concerned with chemistry and chemical interactions. First the properties of gases are introduced, where how temperature and pressure affect the gas volume will be discovered. The next topic concerns the basic ideas of chemical reactivity, where the extent and rate of chemical reaction will be determined by the evolution of a gas. The third experiment will introduce a battery chemistry, where the students will learn about ions, electrolytes and how a battery converts chemical energy into electrical energy. The final experiment is an engineering challenge where student teams will combine chemical reaction with basic mechanics concepts learned in Sections A and B to construct a car that uses the thrust produced by a gas producing chemical reaction to accelerate a small vehicle.

Exp. 15: Charles Law and Boyles Law.

The expansion/compression of air is measured using a student built apparatus that includes a simple pressure gauge and flow meter. The effect of pressure on volume (i.e. Boyle’s law) and the effect of temperature on the volume of air (i.e. Charles’s law) can be determined using this apparatus. Students use their data to discover the ideal gas law.

Exp. 16: Chemical Interactions: Forming CO2.

The reaction of sodium bicarbonate (i.e. baking soda) with acetic acid (i.e. vinegar) to produce carbon dioxide gas is studied using a simple glassware apparatus assembled by the students. Both the extent of reaction and the rate of reaction are investigated. Students can then discover how sodium bicarbonate reacts with other common kitchen/household acids such as citric acid (i.e. oranges and lemons), ascorbic acid (vitamin C), etc.

Exp. 17: Chemical Reactions: Battery Chemistry.

Student teams will measure the voltage and current produced by a simple chemical battery. The students will learn that (i) the voltage produced by a battery only depends upon the chemical reactions that occur between the electrolyte and the anode and cathode and (ii) the current generated is proportional to the area of the electrode surface.

Engineering Challenge: Chemical Reaction Powered Car (Chem-E Car.

This is the third engineering challenge and combines the previous three chemistry modules (Exp. 15-Gas Laws, Exp. 16-Chemical Interactions, Exp. 17-Chemical Reactions). Students will use a chemical reaction producing carbon dioxide to provide thrust to a small vehicle. The motion of a toy car will result from a carbon dioxide producing reaction while vehicle dynamics is dependent upon friction forces in the wheels and air drag. This is an opportunity for the school to have a competition between the cars built by different student teams.

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[accordion clicktoclose=”true”] [accordion-item title=”E. Electricity”]

The next set of 5 experiments are concerned with electricity, electrical circuits, and electrical components.

Exp. 19: Electric Potential.

In this experiment students study the conversion of chemical energy into electrical energy using electrochemical cell potential resulting from oxidation-reduction reactions. They investigating how batteries create an electric potential, a force to push electrons through an electric circuit, and identify the role electrons play in electrical energy by studying Coulomb’s law, and its application to the flow of electrical charge through an electrical circuit.

Exp. 20: Fundamentals of Electric Circuits.

In this experiment students study the relationship between electrical current, resistance and electric potential. They will set up an electrical circuit where the amount of resistance can be manipulated, and investigate how the total resistance and capacitance of a circuit changes based on the arrangement of components in series with one another or in parallel to one another.

Exp. 21: Electromagnets and Motors.

In this experiment students study electromagnetic forces, focusing on the properties of magnets, and learn about magnetic fields and how current carrying wires exhibit properties of magnetism. A review of the torque associated with rotational motion leads to a discussion of electromagnetic moments, prior to investigating brushed DC electric motors.

Engineering Challenge: DC Motor Control.

This is the fourth engineering challenge and combines the previous three electricity modules (Exp. 19-Electric Potential, Exp. 20-Fundamentals of Electric Circuits, Exp. 21-Electromagnets and Motors). In this activity students engage in a competition to determine who can design and build a Mini EV Racer for competing in a series of challenges (fastest speed, slowest speed and steepest incline). Students will be assessed on their ability to create a PWM circuit that exhibits adjustable pulse width control of a their Mini EV Racer, observable in course completion times.

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[accordion clicktoclose=”true”] [accordion-item title=”F. More Advanced Mechanics Topics”]

Experiments are under development.

This final set of topics in mechanics are more advanced and can be used at the teacher’s discretion. They can be part of a general physical science course for student that would benefit from an additional intellectual challenge. Or, they could be part of a more advanced applied physics course or used as suggestions for a science fair project.

Exp. 22: Ball Drop and Fluid Friction.

(Under Development) In this experiment balls of various diameters and densities are dropped into a viscous liquid and the time for the ball to fall a given distance is measured and then the viscosity of the liquid is determined using Stokes Law. Newton’s 2^nd Law (which is the Conservation of Linear Momentum Principle) is introduced where the force of gravity on the ball is balanced by frictional forces from the fluid. In this experiment students drop a ball in a clear tube filled with liquid and measure the rate at which the ball falls. From this data they determine the drag on the falling ball and the viscosity of the fluid. The students will explore the effect of ball diameters and weight of the drag force.

Exp. 23: Ball Launcher Revisited.

(Under Development) In initial Ball Launcher analysis (Exp. 7) the key idea was Conservation of Energy with kinetic energy being converted into potential energy. Now the same experiment will be revisited using Newton’s 2^nd Law where the change in momentum (i.e. velocity x mass) of the ball is changed by the gravitational force and fluid friction that depends upon the ball velocity. In this experiment the effects of ball diameter, density and surface roughness are studied. Students construct a rubber band powered ping-pong ball launcher, where the launch angle and rubber band extension can be controlled. The flight of the ping-pong ball is recorded using a smart phone app, where the video can be slowed down for analysis of position as a function of time. Analyzing the data enables calculation of velocity, understanding of the interconversion between kinetic and potential energy during flight, and effect of air drag on the trajectory of the ball.

Exp. 24: KE/PE/loss – Follow the Bouncing Ball.

(Under Development) During fluid friction (Exp. 22) and sliding friction (Exp. 9) students explored the conversion of mechanical work into thermal energy, i.e. heat. There is another way that mechanical energy can be lost – by internal dissipation in a material. This process will be studied by dropping various balls in a tube and recording how high they rebound. A highly resilient super-ball will show very little amplitude decay between subsequent bounces, a regular rubber ball will show modest amplitude decay between subsequent bounces and a foam ball may show almost not elastic rebound.

Exp. 25: Strength of materials.

(Under Development) The stiffness of materials was studied in Exp. 10, where Young’s modulus was the key material property. The amount of load that material can support before in breaks is call ‘strength’ and it is an equally important material property. The strength of several plastics will be measured.

Exp. 26: Vibration damper: An Engineering Project.

(Under Development) Mechanical energy can be stored in an ‘elastic’ material like shown for deformation of a rubber band in Exp. 6 or bending of a metal beam as in Exp. 10. Energy is dissipated by fluid motion as studied in Exp. 22, where a damper (like used in a door closing assembly) is a mechanical device that dissipates energy. Systems where an elastic spring is connected in parallel with a damper are engineering devices used in a variety of applications, e.g. the spring and shock absorber system in all vehicles. In this experiment a spring-damper system will be constructed and the performance of the system will be analyzed.

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[accordion clicktoclose=”true”] [accordion-item title=”G. Thermal Energy, Melting and Combustion Engine”]

Experiments are under development.

The next set of 3 experiments are concerned with more advanced chemical topics and processes.

Exp. 27: Thermal Energy and Heat Transfer.

(Under Development) Students investigate thermal energy by constructing an apparatus, where a warm metal object is dropped into a well-insulated, stirred water bath. The temperature of the metal block and the water are measured. Metal objects of differing composition, size and shape are investigated. Using this device the students determine the thermal energy in the block, transfer of thermal energy from the block to the water (i.e. conservation of energy) and calculate the heat capacity of the metal. In a more advanced experiment students make a device to measure the heat conduction through a thin slab of material.

Exp. 28: Melting Point & Welding.

(Under Development) Using a melting point apparatus (i.e. a small metal block with a heater, thermometer and a capillary tube filled with a crystal), students measure the melting point of a number of materials, including pure materials, mixtures and alloys. There is a discussion of the melting of various metals that provides an understanding of the periodic chart in the iron, nickel, chromium, aluminum, etc. region that is related to welding. Ideally, the students would have the opportunity to use a virtual welder to see metal melting/solidification in a practical application.

Exp. 29: Combustion Engine – Simulator.

(Under Development) Using a computer simulator, students change reaction conditions in a piston, observing the pressure generated by the reaction as well as movement of the piston. They are able to explore the difference in the piston response with and without heat generation and heat transfer through the piston walls (i.e. the effect of Charles’s Law from Exp. 15 and heat transfer from Exp. 27 and Exp. 28). In a more advanced simulation students will be able to observe the effect of incomplete and/or side reactions that produce undesirable gases like carbon monoxide and NOx. This module will provide an understanding of the periodic chart in the C, H, O, N region.

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[accordion clicktoclose=”true”] [accordion-item title=”H. Optics”]

This set of experiments are concerned with optics.

Exp. 30: Prisms, Lens and Mirrors.

(Under Development) Students are provided with a collection of mirrors, prisms and lenses to be used with a laser pointer (with a red beam for safety). Students then explore how the laser beam is bent by the mirrors, prisms and lenses. The students discover Snell’s law and how it applies to the various optical components.

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[accordion clicktoclose=”true”] [accordion-item title=”Quick List of 28 Hardware Store Science Experiments “]

Quick List of 28 Hardware Store Science Experiments

Mechanics

Mechanical Equilibrium and Conservation of Energy

1. It’s a Balancing Act: Levers
2. Pulleys
3. Energy Storage: Stretching a Rubber Band
4. Adjustable Ball Launcher
5. Center of gravity
6. Material stiffness: beam bending

Friction and Conservation of Linear Momentum

7. Ball drop & fluid friction – Stokes flow don’t enable this
8. Sliding friction
9. Ball Launcher Revisited don’t enable this

Circular Motion and Conservation of Angular Momentum

10. Circular motion & centripetal force
11. Engineering problem: centripetal force with sliding friction and center-of-gravity
12. Gears
13. Torque

More Advanced Mechanics Topics

14. KE/PE/loss: bouncing ball drop
15. Strength of materials
16. Vibration damper don’t enable this

Chemistry

Gas Behavior and Chemical Reaction

17. Charles/Boyles Law – balloon inflation
18. Chemical reaction: kitchen chemistry forming CO₂
19. Chemical car
20. Battery chemistry

Thermal Energy, Melting and Combustion Engine

21. Thermal energy and heat transfer
22. Melting point & welding
23. Combustion engine – simulator

Electricity

24. Simple Electric Circuits
25. Electromagnets
26. Electric motors
27. Battery Operations

Optics

28. Prisms, Lens and Mirrors

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Individual Hardware Store Science Experiments

Organization of Science Experiment Modules.

Exp. 1: Levers – It is a balancing act.

Exp. 5: Pulleys.

Exp. 6: Energy Storage – Stretching a Rubber Band.

Exp. 7: Ball Launcher.

Engineering Challenge: Backyard Roller Coaster.

Exp. 9: Sliding Friction.

Exp. 10: Material Stiffness – Beam Bending.

Exp. 11: Circular Motion and Centripetal Force.

Exp. 12: Torque and Gearing.

Exp. 13: Center-of-Gravity.

Engineering Challenge: Turn Radius.

Exp. 15: Charles Law and Boyles Law.

Exp. 16: Chemical Interactions: Forming CO2.

Exp. 17: Chemical Reactions: Battery Chemistry.

Engineering Challenge: Chemical Reaction Powered Car (Chem-E Car.

Exp. 19: Electric Potential.

Exp. 20: Fundamentals of Electric Circuits.

Exp. 21: Electromagnets and Motors.

Engineering Challenge: DC Motor Control.

Exp. 22: Ball Drop and Fluid Friction.

Exp. 23: Ball Launcher Revisited.

Exp. 24: KE/PE/loss – Follow the Bouncing Ball.

Exp. 25: Strength of materials.

Exp. 26: Vibration damper: An Engineering Project.

Exp. 27: Thermal Energy and Heat Transfer.

Exp. 28: Melting Point & Welding.

Exp. 29: Combustion Engine – Simulator.

Exp. 30: Prisms, Lens and Mirrors.

Mechanics

Chemistry

Communication

Campus

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