# Energy & Work

Arbor Scientific is providing physics and physical science teachers with a collection of student lab activities for the study of Energy and Work. Here you can browse lab activities by title and get teachers notes, student worksheets and a list of equipment and supplies needed for each activity.

## Momentum – Tailgated by a Dart

In this lab, students will learn to estimate the speed of an object by applying conservation of momentum to an inelastic collision. Energy is not lost its transferred from one object to another. Students will fire a dart into the back of the free rolling car and measure the distance of the car, calculate the speed of the dart and car, and measure the mass of the car and dart.

### Required Equipment

Tailgated by a Dart Kit, stopwatch, meterstick, balance

Every day we have to make choices. Sometimes these can be life changing. In the Firing Squad Demo the student you pick to be the target, will have to choose between two dart guns to be shot with!

One of the guns has a steel ball glued to the dart. Standing approximately ten feet from the two loaded guns he or she will need to think like a physicist to make the right choice. Both guns, being essentially identical, push the two different-mass darts with the same force. Which dart will they choose to be shot with?

Here the distinction between the inertia property of mass and its gravitational property is illustrated.

In a follow-up demo, ask the students to predict which dart would hit the ground first if fired downward at the same time from a point near the ceiling.

These two demos help to illustrate the importance mass plays in Newton’s second law when expressed as a=F/m. Ask the students to explain their predictions using this equation, noting that value of ‘F’ in the equations is the force of the springs from the identical guns while the ‘m’ in the equation is the value of the mass of the different darts.

Required Equipment
Dart Gun, 1 inch Steel Ball, Hot Glue

Recommended quantity per lab group: 2

P4-1301
Dart Gun
\$3.25

Recommended quantity per lab group: 1

P1-5003
1 inch Steel Ball
\$1.25

Recommended quantity per lab group: 1

Hot Glue can be used to adhere the steel ball to the dart.

## Pulleys: Fixed, Movable and Systems

 Students construct a complex system of six pulleys and determine its ideal mechanical advantage. They then use the system to lift a weight and measure the work input and energy output of the system. They calculate the actual mechanical advantage and efficiency of the system and evaluate the system for sources of loss. Required Equipment Workshop Stand, Physics Workshop Pulleys Lab, Spring Scale Set, Meter stick, Hooked Masses. Download Teacher Notes and Student Worksheets

# Specific Heat Inquiry

One characteristic or property of all solids and liquids is something called the Specific Heat, abbreviated as Cv. This quantity represents the amount of heat required to raise or lower a given quantity (a gram or a Kilogram) by one degree. Water has an extremely high Specific Heat (1 calorie per gram per degree C). A rule of thermodynamics (the study of heat and heat transfer) is that when two objects are placed in contact, they will eventually reach thermal equilibrium. Energy (heat is a measure of energy in a substance) flows from the warmer object or liquid to the cooler one until they both reach the same temperature (equilibrium). When we mix liquids, this rule must be obeyed.

Required Equipment
500ml Beaker, 1000ml Beaker, Thermometer +20 to +110C, Hot and Cold Water.

Acknowledgements: Thank you to Dr. J.R. Harkay author ofPhenomenal Physics for providing this student inquiry activity. Adapted from “The Seven Percent Solution: Mixing,” an Inquiry Exercise by J. R. Harkay. See www.PhenomenalPhysics.comfor more information on the complete Guided Inquiry Curriculum. Dr. Russell Harkay
Keene State College
New Hampshire

Any tap water will work for the “Hot and Cold Water” required in this lab. Non-toxic antifreeze can also be used to add another aspect to this lab.

## Stable Mates Inquiry

We might ask why Nature chooses to arrange things according to certain patterns. In this exercise, you will be messing about with some special marbles. Let’s call them “concentrically constructed dipolar spheroids” for now. Your task is to determine how they “work”, how to test for stability of assembled structures, and to determine which structures are the most stable. You will also take a look at the forces between the marbles and groups of marbles when they interact.
Required Equipment
Magnetic Marbles.

Acknowledgements: Thank you to Dr. J.R. Harkay author ofPhenomenal Physics for providing this student inquiry activity.Adapted from “Stable Mates,” an Inquiry Exercise by J. R. Harkay. See www.PhenomenalPhysics.com for more information on the complete Guided Inquiry Curriculum.

Dr. Russell Harkay
Keene State College
New Hampshire

## Conservation of Energy: Racing Marbles

 A marble will roll on different paths, starting and ending at the same height. Students will predict and then measure the final velocities of the marble. Ramp A is the nearly horizontal ramp, and Ramp B dips down in the middle. Because the ramps start and end at the same elevation, a marble rolled on Ramp A will end with the same velocity as one rolled on Ramp B, even though they take different times to complete the trip. Required Equipment Physics Workshop Racing Marbles Lab, Data Logger, 2 Photogates. Download Teacher Notes and Student Worksheets

Radiant heat travels in the form of waves. No physical contact between objects is needed to transfer heat by radiation. Students will fill black, white, and silver cans with water, and observe the temperature change in the water when the cans are placed under a bright lamp. The cans are being heated by radiation, and the color of the outer finish of the cans determines the efficiency with which they absorb the heat energy. The white and silver cans reflect most of the rays that strike them (visible and non-visible), so they will heat much more slowly than the black can.

### Required Equipment

Radiation Cans, Student Thermometer, Stop Watch, Heat Lamp or Bulb Base 200 Watts with Bulb.

The “Heat Lamp” required for this lab is readily available at your local hardware store. If you instead choose to use the 200 Watt Bulb Base than it is necessary to obtain a 200 watt bulb which can be found at your local hardware or convenience store.

## Heat Transfer

Ice Melting Blocks! Heat can be transferred by conduction, convection, or radiation. In this experiment, students will discover the different rates at which materials can conduct heat. Aluminum is a better conductor of heat than high-density foam.

Required Equipment
Ice Melting Blocks, Ice Cubes.

## Popper Energy

Students will calculate the potential and kinetic energy of a popper toy using simple formulas. Potential energy is found by observing the maximum height. Kinetic energy is found by using a dynamics formula to find the popper’s starting velocity. Students will find that the popper reaches a greater height than it should, given the amount of kinetic energy it started with! The discrepancy is resolved by finding the amount of energy stored in the elastic deformation of the popper.

Required Equipment
“Popper” Toy, Meter Stick, Balance, Pencil.