MOMENTUM

MOMENTUM

MOMENTUM

Momentum is a useful quantity to consider when bodies are involved in collisions and explosions. It is defi ned as the mass of the body multiplied by its velocity and is measured in kilogram metre per second (kg m/s) or newton second (N s).

p = m v

p = momentum (kg m/s)

m = mass (kg)

v = velocity (m/s)

MOMENTUM

• Is vector (have magnitude and direction)

Multiple Choice

The momentum of an object depends upon the object's ___________&_____________.

• size and shape

• mass and speed

• mass and veloctiy

• mass and energy

Multiple Choice

If an object has a velocity of 15 m/s and a momentum of 30 m/s, what is its mass?

• 450 m/s

• 2 m/s

• 4,500 m/s

• .5 m/s

Multiple Choice

The equation to calculate momentum is

• p=mv
• p=1/2mv²
• p=mgh
• p=mg

Multiple Choice

Which object has more momentum?

• Baseball in the pitchers hand

• baseball, lost, in a messy room

• baseball in flight

• baseball in a catchers mitt

Multiple Choice

Which of the following has the MOST momentum?

• rolling ping-pong ball

• rolling bowling ball

• rolling soccer ball

• rolling basketball

Multiple Choice

Determine the momentum of 1000-kg car moving northward at 20 m/s......... 

• 20000 N
• 20000 Joules
• 20000 Kg * m/s
• 20000 kg * m/s north

Multiple Choice

An object has a mass of 5 kg, a displacement of 5 m, and a time of 25 s, what is its momentum?

• 1 kgm/s

• 750 kgm/s

• 25 kgm/s

• 625 kgm/s

Multiple Choice

An object has a mass of 8 kg, a displacement of 10 m, and a time of 40 s, what is its momentum?

• 320 kgm/s

• .5 kgm/s

• 3,200 kgm/s

• 2 kgm/s

Impulse

Impulse is force times time taken

Impulse is also change of momentum

 $I\ =\ F\ \Delta t$  
 $I\ =\ \Delta p\ =\ mv\ -\ mu$ 

Multiple Choice

An impulse depends on

• weight and force

• force and time

• electric charge and time

• none of these

Multiple Choice

An object having a p_i of 30kg m/s has ended with a p_f of 40 kg m/s. What impulse caused this?

• 2kg m/s

• 10kg m/s

• 70kg m/s

• 5kg m/s

Multiple Choice

If the change of momentum of an object is 50kg m/s, we can say the impulse is equal to:

• 0 kg m/s

• 25 kg m/s

• 50 kg m/s

• 100 kg m/s

Multiple Choice

An object has pi of 20 kgm/s and then pf of 30 kgm/s. If it took 2s, what is the force?

• 10N

• 4N

• 5N

• 50N

Multiple Choice

An egg gets dropped from a height of 0.1 meters and cracks. A second egg gets dropped from the same height but this time it lands on a glass of water and does not break. In terms of impulse.

• 1st egg experienced more impulse

• 2nd egg experienced more impulse

• both experienced the same impulse

Multiple Choice

An egg gets dropped from a height of 0.1 meters and cracks. A second egg gets dropped from the same height but this time it lands on a glass of water and does not break. In terms of force and time, the second egg must have experienced...

• more force, but less time

• less force, but more time

• more force, and more time

• less force, and less time

CONSERVATION OF MOMENTUM

 $\Sigma pi\ =\ \Sigma pf$  
m1v1 + m2v2 = m1v1' + m2v2'

Move together: m1v1 + m2v2 = (m1+m2) v'

Multiple Choice

The Law of Conservation of Momentum states that the amount of momentum in a system is ___________________ before and after a collision.

• greater

• decreased

• the same

• unknown

Multiple Choice

Two football players with mass 75 kg and 100 kg run directly toward each other with speeds of 6 m/s and 8 m/s respectively. If they grab each other as they collide, the combined speed of the two players just after the collision would be:

• 2 m/s 
• 3.4 m/s 
• 4.6 m/s 
• 7.1 m/s

Multiple Choice

A 9300 kg railroad car traveling at a velocity of 5 m/s strikes a second boxcar that weighs 5000 kg at rest. At what speed will the second boxcar move?

• 18.6 m/s
• 9.3 m/s
• 7.5 m/s
• 1.86 m/s