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Flashcards in Momentum and Collisions Deck (13)
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What is the equation for momentum?

Momentum = mass x velocity


What is the sign for momentum?



Momentum is a property of what?

Moving objects


What happens to momentum as the mass is increased?

The momentum increases too


What happens to momentum when the velocity increases?

The momentum increases too


What does it mean that momentum is a 'vector' quantity?

It measures size and direction 

(like velocity, but not speed)


What is the formula triangle for momentum? 


Write the units in the momentum equation

momentum (kgm/s) = mass (kg) x velocity (m/s)


What is the equation for momentum before and after a collision? (in a closed system)

Momentum before = Momentum after


What is the fact that momentum after a collision is equal to the momentum before the collision known as?

Conservation of Momentum


State the steps in answering a momentum question in a collision (asking for the velocity)

1. Choose which direction is positive (e.g. to the right)

2. Work out total momentum before collsion by adding the momentum of the 2 colliding objects

3. Add the masses of the objects, and arrange in this formula:

total momentum = combined masses x velocity

4. you should be able to rearrange the equation to get the velocity (as you have the figures of the underlined parts)


Try a practice question:

Two ice hockey players are skating towards the puck. Player A has a mass of 100kg and is travelling right at 6 m/s. Player B has a mass of 80kg and is travelling left at 9m/s.

Calculate the momentum of:

a) Player A

b) Player B

momentum = mass x velocity

right = positive

a) Player A: 100 kg x 6 m/s = 600 kgm/s to the right

b) Player B: 80kg x -9 m/s = 720 kgm/s to the left ( -720 kgm/s )


The second part to the question:

(Player A's momentum = 600 kgm/s, mass = 100 kg, and Player B's momentum = -720 kgm/s, mass = 80 kg)

The two players collide and become joined together.

a) Calculate the speed of the 2 joined players just after the collision

b) State the direction they move

momentum = mass x velocity

right still = positive (although you could change this)

a) 600 kgm/s + - 720 kgm/s = -120

-120 = (100 + 80) x v

-120 = 180 x v

-120 / 180 = v = -0.666... = -0.67 m/s

b) They move to the left