Scientist Name: ______________________________________________ Student #: __________

Unit 4: Momentum – Inelastic Collisions

I. How to use DataStudio TODAY:

II. Lab Procedure

1. Roles:

a. DataStudio Technician

b. Collision Technician

c. Analyst

d. Recorder

e. Calculation and Equation Manipulation (done by all students all the time)

2. Your roles will rotate. Be sure you try each role.

3. Each section will give you starting conditions. Your job is to experiment based on those conditions and not exceed a speed of

1𝑚

𝑠 for either cart.

4. Record your data using DataStudio’s tools.

III. Lab

Directive:

1. Use momentum equations to solve for final velocity of two colliding masses.

2. Use the equation(s) you made and some made-up numbers that fit each Scenario # (S#) to make predictions for final

velocities.

3. Scenario 5 is a challenge. Do it after you’ve accomplished all other data collection.

4. Calculate % change.

5. If you have nothing to do, work on momentum practice problems in your group.

Blue Cart Mass: 250g = __________ kg

Red Cart Mass: 250g = __________ kg

Scenario Parameters: S# Blue Cart Starting Velocity Red Cart Starting Velocity Blue mass Red mass

1 Positive Stationary Just cart Just cart

2 Positive Stationary 1 extra 250g mass Just cart

3 Positive Stationary Just cart 1 extra 250g mass

4 Positive Stationary 2 extra 250g mass Just cart

Positive Negative Just cart Just cart

Theoretical Values and Predictions:

Measured Values:

Analysis:

1. Contrast the starting momentums of Scenario 1 and 2. Even if both original velocities were the same, how would their

momentums be different? Why?

2. How did the difference in starting momentums between Scenario 1 and 2 impact the final velocity of each Scenario?

3. Using the terms: original momentum, mass, inertia, and velocity, contrast the final velocities of Scenarios 2, 3, and 4.

4. Did your measured values align in any way with your predicted values? If so, how?

5. How did your measured values differ from your predicted values (except # value…)? Why do you think they were different?

6. How do you account for the % change in momentum you calculated?

S#

Blue Cart

Starting

velocity:

Red Cart

Starting

Velocity:

Blue Cart

Original

Momentum

Red Cart

Original

Momentum

Total

Momentum

Before

Velocity

After

Collision

Total

Momentum

After

% change in

momentum

1 0 (ideal)

2 0

3 0

4 0

5

S#

Blue Cart

Starting

Velocity:

Red Cart

Starting

Velocity:

Blue Cart

Original

Momentum

Red Cart

Original

Momentum

Total

Momentum

Before

Velocity

After

Collision

Total

Momentum

After

% change in

momentum

1

2

3

4

5 0 𝑘𝑔𝑚

𝑠 0 𝑘𝑔

𝑚

𝑠

% change = |𝑚𝑜𝑚𝑒𝑛𝑡𝑢𝑚 𝑎𝑓𝑡𝑒𝑟−𝑚𝑜𝑚𝑒𝑛𝑡𝑢𝑚 𝑏𝑒𝑓𝑜𝑟𝑒 |

𝑚𝑜𝑚𝑒𝑛𝑡𝑢𝑚 𝑏𝑒𝑓𝑜𝑟𝑒

Scientist Name: _______________________________________________Student #: _________ Date: ______

Momentum: Constant Impulse, Changing Force and Time

Directive: show the following for numbers 1, 2, 4 and 5:

A. Knowns

B. Drawing

C. Equation

D. Solve with equation

E. Plug into solved equation

F. Boxed answer

1. Determine the force experienced by an older model 1950 car with a mass of 500kg traveling at 30𝑚

𝑠

which crashes into a tree. The collision takes 0.05 seconds.

2. The same type of car from the modern day has been engineered for collisions to take twice as long as the

car from 1970. If the car’s mass hasn’t changed, and it crashes into a tree at 30𝑚

𝑠 and stops, determine

the force the car experienced.

3. Record your answers from problems 1 and 2. How do the times of problem 1 and 2 relate? How do the

forces relate?

Object Impact Force Time of Collision

Car from 1950

Modern Car

4. A human inside the car has a mass of 50kg. The human is driving the car of problem 1 (what is their

velocity?). Considering that the car from 1950 doesn’t have a seat belt, the human smashes into the

dashboard, steering wheel, and front windowpane in 0.03s. Find the force that the human experiences.

5. The human of problem 4 is seriously injured and can’t help us for problem 5. We find another human of

the same mass to drive the modern car from problem 2 into a tree. This time, the air bags and seat belt

stop the human instead of the dashboard, steering wheel, and front windowpane. The collision with the

seat belt and air bag lasts 0.1s. Find the force this human experiences.

6. Record your answers from problems 4 and 5. How do the forces of problem 1 and 2 relate? How do the

times relate?

Human in: Impact Force Time of Collision

Car from 1950

Modern Car

7. Find the weight of the human using the force of gravity equation given above. Then fill in the rest of the

table.

Object Weight

(Force of Gravity) Impact Force

How many times the

force of gravity is the

impact force?

Human (mass = 50kg)

�⃗� = 𝑚�⃗�

�⃗�(∆𝑡) = ∆𝑝

�⃗�(∆𝑡) = ∆(𝑚�⃗�)

�⃗�𝐺 = 𝑚�⃗�𝐺

Scientist Name: ____________________________________ Student #: ________ Date: ________

Momentum Culminating Task

Two cars experience a crash on the road. Car 1 is moving East and crashes into Car 2,

Driver 2 is slowly poking the car out of his driveway to see if it is safe to exit the driveway.

The skid marks ( ) show

how far the cars moved when

they were skidding together after

the collision. Car 1 and Car 2 have

approximately equal mass of 500kg

each. The weather that day was mostly cloudy, and there was no water on the ground.

The problem is that Driver 2 is saying that Driver 1 must have been traveling at least 60𝑚𝑖

ℎ𝑟

and didn’t see him coming. Driver 1 insists that he was maintaining the speed limit of 40𝑚𝑖

ℎ𝑟.

Use all information given to you to determine who is telling the truth, and who is lying.

You must show all work clearly for credit.

The best way to approach this problem is to create the K, F, FBDs (1 set for the crash,

another FBD for the skidding), E, S, A. Try not to overthink this problem, break it up into

parts if needed.

Material Skidding

Surface Material Force of Friction For Car 1 and 2

Rubber Concrete (dry) 8000 N

Rubber Concrete (wet) 2500 N

Car 1

Car 2

�⃗�1𝑜 = ?

𝑠 = 6.25𝑚

1𝑚𝑖𝑙𝑒

ℎ𝑜𝑢𝑟= 0.45

𝑚

𝑠

Conversion:

�⃗�𝑇𝑜 = �⃗�𝑇𝑓

𝑝 = 𝑚�⃗�

𝑚∆�⃗� = �⃗�(∆𝑡)

�⃗�𝑛𝑒𝑡 =�⃗�𝑛𝑒𝑡

𝑚

�⃗�𝑓2 = �⃗�𝑜

2 + 2�⃗�𝑠

𝑠 = �⃗�𝑜𝑡 +1

2�⃗�𝑡2

𝑠 =1

2(�⃗�𝑓 + �⃗�𝑜)𝑡

�⃗� =�⃗�𝑓 − �⃗�𝑜

𝑡

Equations:

Car 1

Car 2