PhysicsLAB: Conservation of Energy and Vertical Circles

The purpose of this lab is to investigate the behavior of a metal, dye-cast hot-wheels car moving through a loop-the-loop.

During this investigation, we will make use of energy methods as well as centripetal acceleration.

Refer to the following information for the next three questions.

Part 1. Initial measurements

What is the inner diameter of the track's loop-the-loop in centimeters?

What is the radius of the loop-the-loop in centimeters?

What is the mass of your car in grams?

Refer to the following information for the next three questions.

Part 2: Initial Calculations

Using the properties of vertical circular motion, calculate the critical velocity, in m/sec, needed by the car to travel around the loop-the-loop without losing contact with the track. Show your calculations.

Using conservation of energy calculate the ideal height, in meters, from which the car should be released so that it will successfully complete the loop-the-loop. Show your calculations.

How much initial potential energy, in Joules, will the car posses as it begins its trip down the track?

Refer to the following information for the next two questions.

Part 3. Experimentation

After setting up the track so that the car is able to be released from the height calculated in Part 2 above, release the car to test if it is able to successfully make it through the loop-the-loop. Repeat this at least three times. Did the car remain in contact with the track through the loop-the-loop?

yesno

Describe what happened.

Now increase the height of the track by small intervals (1 to 2 cm) checking to see if the car successfully completes the loop-the-loop. Record your results in the table below.

description of behavior

intial height
(cm)

ending height
(cm)

does not make it, falls from the track

makes it but occasionally loses contact with the track

makes it and stays in contact with the track throughout the loop

Refer to the following information for the next three questions.

Part 4: Conclusions

Using the final value in your chart above for when the car was just able to complete the loop-the-loop and still remain in contact with the track calculate the car's experimental potential energy at the top of the track.

Determine the difference between the initial PE (in Part 2) and the experimental PE (Part 4) actually needed for the car to complete the loop-the-loop.

What does this numerical difference represent?