Momentum Basics
The units of Momentum are ________.
kg*m/s
What happens to the force experienced by an object as the time of a collision increases?
the force decreases
Impulse is equal to the product of ______ and _____.
force and time.
Elastic collisions are ______.
a. bouncy
b. sticky
a. bouncy
Inelastic collisions are ______.
a. bouncy
b. sticky
b. sticky
A 10kg object is pushed away from a 5kg object in an explosion. Which object experiences the greater change in its momentum?
Equal. (They both feel the same impulse)
What is the definition of momentum we came up with on the first day of class in this unit?
How difficult it is to stop something.
According to the Impulse-Momentum Theorem, the impulse experienced by an object is mathematically equal to what?
the object's change in momentum
I apply a force of 800N to a 1200kg object for a time of 8 seconds. How much impulse was given to the object?
6,400 kg m/s
In elastic collisions, objects are deformed during the crash. Describe what happens to the objects after the crash.
They return to their original shape.
In inelastic collisions, objects are deformed during a collision. Describe what happens to the objects after the collision.
They stay deformed permanently.
A 10kg object is pushed away from a 5kg object in an explosion. After the explosion, the 10 kg object is moving at 20 m/s. How fast is the 5kg object moving?
40 m/s.
Half the mass, double the velocity.
Momentum is calculated as the product of ____ and _____.
mass and velocity
Two balls of equal mass are both thrown at a wall from the same distance with the same velocity. Ball A hits the wall and sticks, Ball B hits the wall and bounces off.
Which ball experiences the greater impulse and WHY?
Ball B, because it's momentum changed more than Ball A's. (greater change in velocity)
A 1200kg car crashes into a tree and its momentum changes by 10,000 kg*m/s. The time of the crash is 0.5 seconds. How much force did the car feel?
20,000 N
Two objects have an elastic collision. Object A has more mass, Object B has less mass. Which object has a greater change in its velocity?
the one with less mass
Two objects have an inelastic collision. Object A has more mass, Object B has less mass. Which object has a greater change in its momentum?
They have the same change in momentum.
Explain the primary difference between a collision and an explosion (involving two objects).
In an explosion, both objects start next to each other and are pushed apart.
In a collision, the objects start apart and come together.
An object has a velocity pointing to the right. Which of the following MUST also be pointing to the right. SELECT ALL THAT APPLY.
a. the object's momentum
b. the object's acceleration
c. the net force acting on the object
a. the object's momentum
Two bowling balls are dropped from the same height. Ball A lands in the hard dirt and stops. Ball B lands in a big pillow and also comes to a stop.
Which ball experiences the greater impulse and WHY?
Both experience the same impulse because both momentums change by the same amount.
A 1000kg car speeds up from an initial velocity of 10 m/s to a final velocity of 18 m/s in a time of 4 seconds. How much force was moving the car forward during that time?
2000 N
Two objects have an elastic collision. Object A has more mass, Object B has less mass. Which object experiences the greater impulse?
Same impulse.
Two objects have an inelastic collision. Object A has more mass, Object B has less mass. Which object feels the greater force?
Same force.
After an explosion, the total momentum of the system ______.
a. increases
b. decreases
c. stays the same
d. not enough information
c. stays the same
(conservation of momentum)
Which of the following are NOT vectors. SELECT ALL THAT APPLY:
a. mass
b. velocity
c. acceleration
d. time
e. momentum
a. mass
d. time
A car and a bike crash into each other head on. Which experiences the greater force? Which experiences the greater impulse?
(Must get both answers correct)
Both feel the same force AND the same impulse.
A 0.5 kg ball moving at a speed of 10 m/s to the left is hit by a bat and then moves at 18 m/s to the right. The bat hit the ball with 2800 N of force. Calculate the time of impact between the bat and ball.
0.005 seconds
A bowling ball moving to the right collides with a 1 kg basketball that is at rest. Before the crash, the bowling ball's momentum is 25 kg*m/s. After the crash, the basketball has 8 kg*m/s of momentum. How much momentum does the bowling ball have after the crash?
17 kg*m/s.
The total momentum after the crash must add up to 25 kg*m/s.
A 1500kg train moving at 10m/s to the right crashes into another 1500kg train at rest, and they stick together. How fast are they moving after the crash?
5 m/s.
Double the mass, half the speed now!
After an explosion happens between a 5kg and a 10 kg object, the 5kg object has a momentum of 30 kg m/s.
How fast is the 10 kg object moving?
-3 m/s.