Download Momentum Practice Problems - Perez Biology and Physical science

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Momentum Practice Problems
Which is more difficult to stop: A tractor-trailer truck barreling down the highway at 35 meters per
second, or a small two-seater sports car traveling the same speed?
You probably guessed that it takes more force to stop a large truck than a small car. In physics terms,
we say that the truck has greater momentum.
We can find momentum using this equation:
momentum = mass of object × velocity of object
Velocity is a term that refers to both speed and direction. For our purposes we will assume that the
vehicles are traveling in a straight line. In that case, velocity and speed are the same.
The equation for momentum is abbreviated like this: p=m×v
Momentum, symbolized with a p, is expressed in units of kg·m/sec; m is the mass of the object, in
kilograms; and v is the velocity of the object in m/sec.
Use your knowledge about solving equations to work out the following problems. Be sure to show
all your work with units:
1. If the truck has a mass of 2,000 kilograms, what is its momentum? (v = 35 m/s) Express your
answer in kg·m/sec.
2. If the car has a mass of 1,000 kilograms, what is its momentum? (v = 35 m/s)
3. An 8-kilogram bowling ball is rolling in a straight line toward you. If its momentum is 16 kg·m/sec,
how fast is it traveling?
4. A beach ball is rolling in a straight line toward you at a speed of 0.5 m/sec. Its momentum is 0.25
kg·m/sec. What is the mass of the beach ball?
5. A 4,000-kilogram truck travels in a straight line at 10.0 m/sec. What is its momentum?
6. A 1,400-kilogram car is also traveling in a straight line. Its momentum is equal to that of the truck
in the previous question. What is the velocity of the car?
7. Which would take more force to stop in 10 seconds: an 8.0-kilogram ball rolling in a straight line
at a speed of 0.2 m/sec or a 4.0-kilogram ball rolling along the same path at a speed of 1.0 m/sec?
8. The momentum of a car traveling in a straight line at 20 m/sec is 24,500 kg·m/sec. What is the
car’s mass?
9. A 0.14-kilogram baseball is thrown in a straight line at a velocity of 30 m/sec. What is the
momentum of the baseball?
10. Another pitcher throws the same baseball in a straight line. Its momentum is 2.1 kg·m/sec. What
is the velocity of the ball?
11. A 1-kilogram turtle crawls in a straight line at a speed of 0.01 m/sec. What is the turtle’s
momentum?
What would cause more damage? An object with a mass of 2 kg traveling at a rate of 10 m/s that
stops in 1/100th of a second, or 1/1000th of a second?
You probably guessed that the force produced in the smaller amount of time will be a lot greater
We can find impulse using this equation:
Impulse = change in momentum
Impulse can be further broken down in to force x time
The equation for impulse is abbreviated like this: ft = mv
Ft is impulse, mv is change in momentum, m is mass, and v is velocity
Use your knowledge about solving equations to work out the following problems. Be sure to show
all your work with units:
12. An object protecting an egg hits the ground with a velocity of 2.5 m/s, and has a mass of 0.5 kg.
The time of the collision is 0.003 seconds. That is the force on the object
13. A different egg drop device hits with a force of 500N, with a collision time of 0.003 seconds and a
mass of 0.25 kg. What is the velocity it was traveling at collision?
14. When a car hit a wall traveling 24.6 m/s (55 mph), the collision took 0.056 seconds. The car had a
mass of 4500kg. What was the force the car hit the wall with?
15. If the same car could make the length of the collision increase to 0.125 seconds, how much would
the new force be?
What would happen if 2 cars hit each other? We have learned that the law of conservation of
momentum tells us that the momentum will be the same before and after the collision
Let’s remember that Momentum is mass times velocity, or p = mv
The law says that Pb = Pa where Pb is momentum before and Pa is momentum after
So, (m x v)b = (m x v)a
This works with multiple objects colliding.
16. A bowling ball with a mass of 6.4 kg (14 lbs) that is traveling at 7.6 m/s (17 mph) strikes a pin that
weighs 1.6 kg (3.8 lbs). How fast will the pin fly away?
17. Two ice skaters push off against one another starting from a stationary position. The 45-kg skater
acquires a velocity of 0.375 m/s to the right. What velocity does the 60-kg skater acquire?
18. A 42,000 kg train car is traveling at 12m/s. It hits another train car and they stick together. The 2
cars move away with a velocity of 7 m/s. what was the mass of the 2nd train car?
19. Superman, with a mass of 150kg, goes into outer space to push a 125000kg alien spaceship out of
stationary orbit. He uses his super strength and pushes the ship away ay at speed of 150m/s. What is
the speed of Superman after his big push?
20. A 25,000kg asteroid is flying towards the Earth at a speed of 1500.0m/s. How much Silly Putty
would it take to stop the asteroid if we launched it at a velocity of -100.0m/s? Assume the Silly Putty
sticks to the asteroid.
Momentum Problems – Answer Key
(CPO worksheet)
Remember : I am much more interested in your work. I’ve provided the answers so you can make
sure that your work is leading you in the right direction.
1. p = 70,000 kg m/s
2. p= 35,000 kg m/s
3. v= 2 m/s
4. m = 0.5 kg
5. p= 40,000 kg m/s
6. v = 28.6 m/s
7. ball 1: 1.6 kg m/s ; ball 2: 4 kg m/s
8. m= 1225 kg
9. p= 42 kg m/s
10. v= 15 m/s
11. p= 0.01 kg m/s