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LAB: Momentum Bashing
Introduction:
To better understand what happens in a car crash, it helps to see how force, inertia, and
velocity are related in a property called momentum. The amount of momentum that object
has depends on its mass and velocity. In this activity, you will determine how increasing mass
affects the bashing power of marbles.
To find out how much momentum an object has, use the formula:
p (momentum) = mass x velocity
Pre-lab Questions: Answer in complete sentences.
1. What determines if one car has more momentum than another in a two-car collision?
2. Does increasing an object’s mass increase its momentum?
3. How does momentum relate to inertia?
Materials
o Ruler with center groove
o 4 marbles of the same size
o 5-oz plastic cup
o Stop watch
o 3 beam balance or electronic scale
o Scissors
o Meter sticks
o Books to support track
Procedure
1. Cut a 3.0 cm square section from the top of the
cup (as shown to the right).
2. Place a ruler with one end on a textbook (about
3.0 cm height) and the other end resting on the
desk.
3. Place the 3.0cm opening of the cup on top of the
ruler end that is on the desk.
4.
5.
6.
7.
8.
9.
Place a meter stick alongside the cup to measure the distance (in cm) the cup moves.
Position one marble in the groove at the maximum height of the ruler.
Release the marble and observe the cup.
Measure the distance the cup moved to the nearest 0.1 cm.
Perform three trials for 1, 2, and 3 marbles and average the results.
Record your data in the table provided.
Data Table 1: Glass Marble – Distances
# of
Marbles
1
Mass of
Marbles
Distance Cup Moves (cm)
Trial 1
Trial 2
Trial 3
Average Distance Cup
Moves (cm)
2
3
Analysis – Answer in complete sentences.
1. Compare your data for the glass marbles and different sized marbles. How are the
results different? Explain your answer using concepts of momentum and inertia.
2. Describe the general relationship between the number of marbles hitting the cup and
the distance the cup moves.
3. What if the cup were made out of steel? How would your data be different for the trials
with the glass marbles? Explain your answer using concepts of momentum and inertia.
4. Explain why a 40,000 kg truck traveling at 2 miles per hour has the same momentum
as a 2,000 kg SUV traveling at 40 miles per hour.
5. What is the momentum of a marble that has a mass of 1.2 kg and a velocity of
+8.5m/s? Calculate the impulse needed to stop this marble.
6. Imagine two cars on the road. A car with a mass of 700kg is traveling at a velocity of
30 km/hour toward another car with a mass of 500kg. The second car is traveling at a
velocity of 40 km/hour. Using the formula for momentum (p=mv) which car has more
momentum? What will be the outcome of this collision?
7. Using the formula, determine the momentum of a...
a. 60-kg halfback moving eastward at 9 m/s.
b. 1000-kg car moving northward at 20 m/s.
c. 40-kg freshman moving southward at 2 m/s.
8. Where is Newton’s 1st law of motion at work in this lab activity?
9. Where is Newton’s 2nd law of motion at work in this lab activity?
10. Where is Newton’s 3rd law of motion at work in this lab activity?
Conclusion:
3-5 sentences telling about the information learned from this lab activity.