Activity: Air Track Simulation
Prior Knowledge Questions: Imagine going to a bowling alley with a bowling ball and a ping pong ball.
1) Why is a bowling ball better for knocking down pins than a ping pong ball? ______
______
2) Which do you think would knock down more pins, a bowling ball moving 10 meters per
second or a bowling ball moving 10 centimeters per second? ______
3) What two factors seem to most affect the amount of damage that occurs in a collision?
______
Simulation warm-up:
An air track is a device that helps scientists study motion. Air comes out of holes in the track, allowing the gliders to move with minimal friction.
1) Click “go” to view the collision between the two gliders. What you do see? ______
______
2) Click “momentum values” to see the velocity and momentum before and after the collision.
A. What is the velocity of the red glider before the collision? ______After? ______
B. What is the momentum of the red glider before the collision? ______After? ______
C. What is the velocity of the green glider before the collision? ______After? ______
D. What is the momentum of the green glider before the collision? ______After? ______
E. What do you notice about the total momentum before and after the collision? ______
______
Activity:
1) Explore: The simulation allows you to adjust the mass and initial velocity of each glider. Set up each of the following scenarios and describe what happens when the gliders collide.
A. The gliders have the same mass but different velocities. ______
______
B. The gliders have the same mass and one glider is stationary (not moving). ______
______
C. The gliders have the same velocity (but in opposite directions) and different masses.
______
2) Calculate: An object’s momentum (p) describes how hard it is to stop. Momentum is equal to the product of mass and velocity: p = mv. If mass is measured in kilograms and velocity in meters per second, the unit of momentum is kilograms × meters per second, or kg·m/s.
A. What is the momentum if the mass is 1.5 kg and the velocity is 4 m/s? ______
Adjust the mass and velocity of the red glider and look in the “momentum values” box
to check your answer.
B. What could you do to increase the momentum of the red glider? ______
______
3. Gather data: Set the red glider to m = 3 kg and v = 2 m/s. Set the green glider to m = 2 kg and v = -4 m/s. Fill in the left table, run the collision, and then fill in the right table.
Before collision
Mass / 3 kg / 2 kg
Velocity / 2 m/s / -4 m/s
Momentum
After collision
Mass
Velocity
Momentum
What was the total momentum (look at the bottom of the “momentum values” box) before the collision? ______After? ______
4. Experiment: Set up 3 collisions using any combination of masses and velocities you like. (the only rule is that the gliders must collide). Record the mass, velocity, and momentum of each glider before and after the collision. Then, find the total momentum. Remember to include units.
m / v / p / m / v / p / Total momentum
Before collision
After collision
Before collision
After collision
Before collision
After collision
5. Analyze: Look at the 3 collisions you did above. What do you notice about the total momentum of the 2 gliders before and after each collision?
______
______
6. Explore on your own: Near the top left, you can change the elasticity. So far you have done the simulation with e = 1 (elastic collisions). Change e = 0 (inelastic collisions) and try a few inelastic collisions.