Concepts
Momentum
Impulse
Collisions
Random
100

What is the difference between elastic and inelastic collisions?

Elastic: kinetic energy is conserved; Inelastic: kinetic energy is not conserved (objects may stick).

100
If you decrease the velocity does the momentum increase or decrease?
decrease of momentum
100

What is equal to the change in momentum?

impulse

100
What is conserved in a collision?
Momentum
100
When objects push away from each other, momentum is....
conserved
200

Define the units for momentum, impulse and force.

Momenutm=kgm/s Impulse=Ns Force=N

200
A person carrying groceries doubles their velocity but halves their mass when her groceries fall to the floor. What happened to their momentum?
Their momentum is the same.
200

A force of 4 N is applied to a ball for 0.75 s. What is the impulse?

3 Ns

200

In a vehicular collision with no external forces, this quantity remains constant throughout the collision.

Total momentum of the system

200

In any collision, momentum is always conserved, but this form of energy may or may not be conserved depending on the collision type.

Kinetic energy

300
Which has greater momentum: a train at rest or a moving skateboard? Explain
The moving skateboard since the train has no velocity and p=mv it would have no momentum.
300
Determine the momentum of a ... 1000-kg car moving northward at 20 m/s. Show work.
What is : p = m*v = 1000 kg*20 m/s p = 20 000 kg•m/s, north
300

A model jet rocket applies an impulse of 20 Ns over 3 s interval of time. What is the force applied?

6.67 N

300

When two cars collide and move together after impact, this type of collision has occurred.

Perfectly inelastic collision

300

During PE class, a 60 kg student on rollerblades rolls at 2.5 m/s toward a stationary 40 kg classmate also on rollerblades. After the collision, the first student slows to 1.0 m/s, and the second rolls forward at 2.25 m/s. What is the total momentum before and after the collision?

150 kg m/s

400

How airbags reduce injuries in terms of the impulse-momentum theorem?

Airbags increase the time over which the momentum changes, reducing the force experienced by passengers.

400

According to the Guinness Book of World Records, the fastest recorded baseball pitch was delivered by Nolan Ryan in 1974. The pitch was clocked at 45.0 m/s. Determine the momentum of a 0.145-kg baseball.

What is: p = m*v = 0.145 kg*45.0 m/s p = 6.52 kg•m/s)

400

What is the impulse of 1kg object with an initial velocity of 2 m/s and a final velocity of 7m/s?

5 Ns

400

Traffic accident investigators use conservation of momentum to determine these quantities before a collision occurred.

Velocities of the vehicles before collision

400

During PE class, a 60 kg student on rollerblades rolls at 2.5 m/s toward a stationary 40 kg classmate also on rollerblades. After the collision, the first student slows to 1.0 m/s, and the second rolls forward at 2.25 m/s. What is the total kinetic energy before and after the collision?

Before: 187.5 J

After: 131.25 J

500
Why doesn't an egg break when thrown on a sheet?
The sheet gives so the egg has more time to slow down reducing the force it feels.
500

A 300 kg snowmobile is traveling at 30 m/s. How fast would a 200 kg snowmobile need to travel to have the same momentum?

45 m/s

500
A 3kg object slows from 62m/s to rest in 20 seconds. What force does it feel?
-9.3 N
500

A moving cart hits a stationary cart, and they bounce off. What type of collision has occured?

Elastic collision

500

During PE class, a 60 kg student on rollerblades rolls at 2.5 m/s toward a stationary 40 kg classmate also on rollerblades. After the collision, the first student slows to 1.0 m/s, and the second rolls forward at 2.25 m/s. Are momentum and kinetic energy conserved? What type of collision is this?

Momentum is conserved, but kinetic energy is not.
Inelastic collision

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