Collision phet lab

Phet simulation Lab: 1D- collision

DO Now (5 mins)

• PhET Collision Lab - Elastic 1D (crossout Elastic and write 1D collision)

• Go to https://phet.colorado.edu/sims/html/collision-lab/latest/collision-lab_en.html

• Complete set-up: row 1,2, and 3 in as mentioned in your worksheet.

Guided trial

• ​Check if you have the variables set as per #4

• Click the play button and answer the questions in the next slide

Open Ended

What do you think the black arrow means?

Open Ended

What was the total momentum before the collision AND after the collision?

Hint: px refers to the momentum of each ball. The total momentum is both of them added together. In this case it would be “-.25 kg m/s” before the collision.

Open Ended

What was the kinetic enrgy before the collision AND after the collision? (Hint: KE in the bottom left is the total KE)

5) Describe what happens in your own words

This is an elastic collision (elasticity=100%). As seen in the black arrow, the total momentum is the vector sum of the two momenta (p1 and p2). The total momentum before collision and after collision is the same i.e. the total momentum is conserved during an elastic collision. The total KE is also conserved during elastic collision.The objects bounce back or separate.

Independent practice

6) Change the table as below

Open Ended

What happened to the little black arrow ?

Open Ended

What was the total momentum before the collision AND after the collision?

Hint: px refers to the momentum of each ball. The total momentum is both of them added together. In this case it would be “-.25 kg m/s” before the collision.

Open Ended

What was the kinetic enrgy before the collision AND after the collision? (Hint: KE in the bottom left is the total KE)

7) Describe what happens in your own words

This is an elastic collision (elasticity=100%). The little black arrow disappeared because the total momentum is 0kgm/s. The total momentum before collision and after collision is the same i.e. the total momentum is conserved during an elastic collision. The total KE is also conserved during elastic collision.The objects bounce back or separate.

Open Ended

What was different between scenario #4 and #6?

Open Ended

Why do you think that was?

8) What was different between the two scenarios? Why do you think that was?

In scenario #6 the velocities were just exchanged between the objects after collision which was not the case in scenario #4. I think due to the same mass of the two objects and conservation of momentum, they simply exchanged velocities during collision.

Stamp

​What is elastic collision?

A collision is elastic when the objects bounce off each other. For elastic collisions the total momentum and the total kinetic energy of the system are conserved (meaning it is same before and after collision.)

Inquiry trial 1 (elasticity=50%)

Set the variables according to the table.

50 % elastic (OR partially elastic) collision is most common in our natural world.

Move the Elasticity slider to 50%

Predict

Test

​​***Fill in the momentum column in the above table***

Open Ended

What is a partially elastic collision?

Open Ended

How is it different from elastic collision?

Stamp

​What is a partially elastic collision?How is it different from elastic collision?

A collision is partially elastic when the the total momentum is conserved but some KE is lost but they still bounce away from each other. During elastic collision both i.e. momentum and KE are conserved but for partially elastic collision does not conserve the kinetic energy during collision.

Open Ended

What happens to the KE during partially elastic collision?

Inquiry trial 2 (elasticity=0%)

Set the variables according to the table.

0 % elastic (OR completely inelastic)

Move the Elasticity slider to 0%

Predict

Test

​***Fill in the momentum column***

Stamp

​What is an inelastic collision? How is it different from elastic collision?

During an inelastic collision, the objects stick together and become one mass. It loses a large amount of kinetic energy during collision. The system's total momentum is conserved. During elastic collision, the objects bounce off each other and the total kinetic energy of the system is conserved.

​Exit ticket (5 mins)