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MatchBox Cars Energy lab Name: _____________________________ 1. Find the mass and name of the car selected. Car: ______________________________ mass: __________________________ 2. Setup the wooden ramp by adding books underneath one end. Use tape to identify your starting point on the ramp. You will need to identify the half way point on the ramp. Use a piece of Duct Tape to allow a smooth transition to the table top. You will need a long run-out area. Tape a meter stick down to measure the run-out distance. 3. We want to determine the potential energy of the car at the top of the ramp (takeoff point). You will need to measure the height of the car’s frame to the table top (in meters).
Height: ___________________ P.E. = mass x gravitation acceleration (9.8) x height (in meters)
P.E. ________________________________________________J
4. Allow car to run down the ramp several times to make sure it rolls straight and makes a smooth transition onto the table top. You may want to use books or meters sticks on the side of the ramp.
5. Use your stopwatch to time the car to the half-way point and to the end of the ramp. You will need to do this several times to get an average. This will allow us to calculate the velocity of the car. We will do it another way later.
Time to halfway point: __________________s time to end of ramp: _______________s
Velocity = distance / time
Velocity at halfway point: _________________ m/s velocity at end of ramp: ______________m/s
K.E. = ½ m v2
K.E. at halfway point: _______________ J K.E. at end of ramp: ______________J
6. Allow the car to roll down the ramp several times and measure the roll out distance.
Average roll-out distance: _______________________m
7. We know that the kinetic energy (K. E. = ½ m v2) = Force of friction x roll-out distance. Using your K.E. calculated earlier and the roll-out distance calculate the force of friction that is being applied to the car to make it stop rolling.
K.E. / roll-out distance = ___________________N (frictional force)
Second Lab Kinetic Energy of a Racing Car Name: ___________________________ Class: ___________
Introduction: The law of conservation of energy states that energy cannot created or destroyed, but its form may change. Does the kinetic energy of the car at the bottom of the ramp, found by the formula: KE = ½ m v2 equal the potential energy at the top of the ramp? PE = m g h. Should the angle of launch affect the results?
Procedure: 1. Place the track on the desk and use books to elevate it to a 10 º angle (as close as is possible). Place the launch system block underneath the track so that you can use the car to pull the rubber band back to each of the starting positions. Practice launching the car several times to see the result. One student will launch the car, another will time the car from start to finish, and another will mark and measure the distance traveled by the car. Another student will record all the data (angle of inclination, car type, rubber band position, time from stopwatch, and distance traveled.
2. Find the mass of each car using the lab scales. Be certain you know which car is which.
3. Your group will need to complete the following: a) 2 or 3 different rubber band pull back positions (Forces) b) 2 or 3 different angles of inclinations c) 2 or 3 different cars d) 2 or 3 different trials for each setup (to get averages)
4. Each student will need to copy all data from the student recording the data. Students will be working alone during the calculation part of the lab.
5. Trial 1: car: ______________________ launch position: ______________________
Angle of track: ____________________ time: ____________________
Distance traveled: ___________________________
You will need to repeat this data chart many time (once for each trial)
6. Calculate the average velocity of the car (Vav) by dividing distance rolled by time taken:
7. Calculate the initial velocity at launch (Vi) by multiplying the Vav by 2.
8. Calculate the KE at launch by using the formula: KE = ½ m v2 where v is the initial velocity.
9. Measure the height of the car above the table top at launch position and the location on the ramp where it stopped. Subtract those two measurement to find the height of the car.
10. Calculate the PE of the car at the top of the ramp: PE = m g h where m = mass of car, g = 9.8 m/s2, and h equals the height from #9.
11. Calculate the percent difference between the answer for the KE and the PE (subtract your answers, then divide by the largest of the two, then multiply by 100).
12. Which combination of car, ramp angle, and rubber band position gave the lowest percent difference.
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Page Last Updated: Friday March 02, 2007 Webmaster: Larry Jones Pickens County School District |