Name: ___________________________
Period: __________
Date: _________________________
Lab Partners: _________________________________________________________________________________________
Mini-Lab: Elastic Collisions
Mr. Fineman
Objective:
Students will predict the motion of carts undergoing elastic collisions, test their
predictions, and explain observed results based on the Law of Conservation of Momentum.
Materials:
(1) Green PASCO GoCar
(1) 250 gram “long-mass”
(1) Non-Green PASCO PASCar
(1) Meter Stick (For Reference)
Purpose
We have learned a great deal about Elastic Collisions, Inelastic Collisions, and The Law of
Conservation of Momentum. There are a few scenarios involving these types of collisions
that we should learn about. As opposed to talking about it, why not actually test these
collisions out?
Procedure
Note: Your Non-Green PASCO PASCar is either red or blue. At the top on one of the
sides of the cart is a small button. Pressing this releases a plastic plunger to aid with
elastic collisions. Please ensure that this plunger is out during these collision tests.
This plunger will serve as the contact point between the two cars.
Experimentally Determining the Mass of the Motion Carts
With our first test, we will be able to determine the approximate mass of these
motion carts by using the formula for an elastic collision, as well as our skills of
observation.
Pre-Question 1: What is the formula for an elastic collision?
Take the Green PASCO GoCar (Green Cart) and place it in the middle of your lab
table. Ensure that the green cart is at rest. Now take your Non-Green PASCO PASCar
(Non-Green Cart) and roll it towards the green cart, allowing the two carts to collide.
Using the space below, draw and predict what you think will happen after the collision.
Non-Green Cart
Before Collision
Green Cart
After Collision
Name: ___________________________
Period: __________
Date: _________________________
Lab Partners: _________________________________________________________________________________________
Now, test the collision to see if your predictions matched the actual result. Observe
the speed in which the non-green cart rolls away from the collision after the carts have
collided. Use the meter stick to help see the relative speeds of the carts.
1. Relative to the green cart, what do you notice about the speed in which the non-green
cart travels away from the collision? __________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
2. Based on this observation, what can you assume about the mass of both of these carts?
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
Next, take the 250 gram “long-mass” and place it in the tray on top of the green cart.
Ensure that the green cart is at rest. Now take the non-green cart and roll it towards the
green cart, allowing the two carts to collide. Using the space below, draw and predict what
you think will happen after the collision.
Non-Green Cart
Before Collision
Green Cart
After Collision
Now, test the collision to see if your predictions matched the actual result. Observe
the relative speed in which the non-green cart rolls away from the collision after the carts
have collided. Use the meter stick to help see the relative speeds of the carts.
3. Relative to the green cart, what do you notice about the speed in which the non-green
cart travels away from this collision? _________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
4. Based on this observation, as well as the formula for an elastic collision, what can you
estimate the mass of the green and non-green cart to be? __________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
a. How do you know? ______________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
Name: ___________________________
Period: __________
Date: _________________________
Lab Partners: _________________________________________________________________________________________
Motion of Carts with the Same Mass
Collision A - Different Speeds in the Same Direction
Remove the mass from the top of the non-green cart. We now want to test what
happens when our carts collide when they are traveling in the same direction – but at
different speeds.
Non-Green Cart
Green Cart
After Collision
Before Collision
Draw and predict what you think will happen after the collision shown above.
Now create this collision and answer the following questions:
5. Relative to the green cart, what do you notice about the speed and direction in which
the non-green cart travels away from this collision? What did you notice about the
speed and direction of the green cart after the collision? ___________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
a. Based on the formula for an elastic collision, why did this happen?
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
Collision B - Different Speeds in the Different Directions
Let’s now test what happens when our carts collide when they are traveling in
different directions at different speeds.
Non-Green Cart
Green Cart
Before Collision
After Collision
Draw and predict what you think will happen after the collision shown above.
Now create this collision and answer the following questions:
Name: ___________________________
Period: __________
Date: _________________________
Lab Partners: _________________________________________________________________________________________
6. Relative to the green cart, what do you notice about the speed and direction in which
the non-green cart travels away from this collision? What did you notice about the
speed and direction of the green cart after the collision? ___________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
a. Based on the formula for an elastic collision, why did this happen?
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
Motion of Carts with the Different Masses in Different Directions
Take the 250 gram “long-mass” and place it on top of the non-green cart. Using
the picture below as a guide, predict what will happen to the motion of each cart after the
collision below takes place.
Green Cart
Non-Green Cart
Before Collision
After Collision
Draw and predict what you think will happen after the collision shown above.
Now create this collision and answer the following questions:
7. Relative to the green cart, what do you notice about the speed and direction in which
the non-green cart travels away from this collision? What did you notice about the
speed and direction of the green cart after the collision? ___________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
a. Based on the formula for an elastic collision, why did this happen?
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
Name: ___________________________
Period: __________
Date: _________________________
Lab Partners: _________________________________________________________________________________________
Lastly, predict what will happen in the collision shown below.
Green Cart
Non-Green Cart
Before Collision
After Collision
Draw and predict what you think will happen after the collision shown above.
Now create this collision and answer the following questions:
8. Relative to the green cart, what do you notice about the speed and direction in which
the non-green cart travels away from this collision? What did you notice about the
speed and direction of the green cart after the collision? ___________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
a. Based on the formula for an elastic collision, why did this happen?
_____________________________________________________________________________________________
_____________________________________________________________________________________________
Analysis Questions – Answer these at home INDEPENDENTLY or receive a
zero for this lab.
9. How did this mini-lab aid in your understanding of elastic collisions? _____________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
10. Were there any results of the collisions that you found surprising, and you didn’t expect
them to behave as compared to your predictions? If so, which collisions were surprising
and unexpected? _________________________________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
11. In this lab, I asked that you have the plunger out on the non-green cart for the duration
of the lab. Why was it important to have the plunger out while performing these
experiments? How may your results have been affected if you left the plunger inside of
the cart? __________________________________________________________________________________________
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________