MOM – C – Collisions – Inelastic - Lab

Name______

SIMULATION

Go to essential-physics.com/tx

Enter this code: 742 710 4787

Click on the “Investigations”icon

Scroll down and click on “11B: “Collisions” -

Scroll down and click on the FIRST “iPhysics” icon to launch the simulation

Investigation 11B: Collisions

Momentum is conserved in an inelastic collision. In an inelastic collision, however, some or all of the kinetic energy is transformed into other forms of energy (called losses). In this investigation, you will predict the outcome of a perfectly inelastic collision involving one moving ball and one stationary ball (the target).

Part 1: Perfectly inelastic collisions

1.  The interactive model simulates a perfectly inelastic collision between two balls.

2.  [Run] starts the simulation.

[Stop] stops it without changing values. [Repeat] resets the final values to zero and runs the simulation again.

3.  Select an initial velocity for the moving ball. Record it at the top of Table 1.

4.  Run the simulation for different combinations of masses for the red and green balls. For each combination, record the masses and final velocity in Table 1.

5.  Examine the table for patterns in the data.

Table 1: Velocity AFTER the perfectly inelastic collision

In the table below, set the masses of Green & Red balls to the combinations shown and record the singular final velocity for both balls combined after the collision in the corresponding box.

Initial velocity of incident ball m1: __2 m/s____ Initial velocity of target ball m2: 0 m/s

Red target ball, mass m2
Green moving ball
mass m1 / 5 kg / 10 kg / 20 kg / 50 kg / 100 kg
5 kg
10 kg
20 kg
50 kg
100 kg

Questions USE Phrases / Words SUCH AS – “HALF, More than Half, Less than Half”

a.  Describe the velocities before and after the collision when masses are equal.

b.  Describe the velocities (before and after) when the red target ball has more mass.

c.  Describe the velocities (before and after) when the green ball has more mass.

d.  As a result of the collision, does the total momentum of the system increase, decrease, or remain the same? Does the total kinetic energy of the system increase, decrease, or remain the same?

PLUNGER CARTS

Push one of the carts towards a second target cart at rest so that the two carts stick together and move as one.

The first photogate must measures the velocity of the moving cart prior to the collision

The second photogate measures the velocity of the combined mass of carts after the collision.

Before Collision / After Collision
Run / Mass of Moving Cart (kg) / Velocity Moving Cart(m/s) / Mass of Target Car (kg) / Velocity of Target Cart (m/s)
1 / 0
2 / 0
3 / 0
4 / 0
5 / 0
Run / Momentum of Moving Cart (kgm/s) / Momentum of Target Cart (kg m/s / Total Momentum (kgm/s)
1 / 0
2 / 0
3 / 0
4 / 0
5 / 0
/ Run / Mass of Moving Cart (kg) / Mass of Target Cart (kg) / Combined Mass of Carts (kg) / Velocity of Carts (m/s)
1
2
3
4
5
Run / Total Momentum of Combined Carts
( kgm/s)
1
2
3
4
5

1. Which run best exemplifies the law of conservation of momentum. Justify your answer.

Applying new knowledge: Assume all collisions are one-dimensional.

1.  A 10 kg puck initially moving at 20 m/s has a perfectly inelastic collision with a 20 kg puck.

a.  Will the resulting velocity be greater than, less than, or equal to 10 m/s?

b.  Calculate the resulting velocity.

2.  A 2000 kg car traveling at 8.0 m/s has a rear-end collision with a 1500 kg car stopped at a traffic light. The cars lock bumpers and skid off together.

a.  Which of the ranges below is correct for the resulting velocity?

A. 0 m/s < v < 4 m/s B. 4 m/s < v < 8 m/s C. 8 m/s < v < 12 m/s

b.  Calculate the resulting velocity.

3.  Two 10 kg pucks head straight towards each other with velocities of 10 m/s and -20 m/s.

They collide and stick together. Calculate the resulting velocity.

Challenge Questions

4.  Two identical pucks of equal but unknown mass head straight towards each other with velocities of 8.0 m/s and -6.0 m/s. They collide and stick together. What is their resulting velocity?

A. +7 m/s B. -7 m/s C. +1 m/s D. -1 m/s E. cannot be determined

5.  A 1200 kg car traveling at an unknown velocity has a rear-end collision with a 1600 kg car parked in the road. The cars lock bumpers and skid off together at 3.0 m/s. What was the velocity of the 1200 kg car right before the collision?

Sim = Simulatoin Plu = Plunger Carts

Section / Sim A / Sim B / Sim C / Sim D / Plu Table 2 / Plu #1 / AKN 1 / AKN 2 / AKN 2
Points / 5 / 5 / 5 / 5 / 5 / 10 / 5 / 5 / 5

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