What is the formula that links momentum (p), mass (m), and velocity (v)?

p = m x v


p = momentum (kg ms-1)

m = mass (kg)

v = velocity (ms-1)

Answer in your head, out loud, or on paper, then tap the card to flip.

Is momentum a scalar or vector quantity?

Momentum is a vector quantity.

Answer in your head, out loud, or on paper, then tap the card to flip.

What are the units for momentum?

kg ms-1

Answer in your head, out loud, or on paper, then tap the card to flip.

What is the principle of conservation of momentum?

The total momentum before a collision is equal to the total momentum after the collision.


total momentum before collision = total momentum after collision

Answer in your head, out loud, or on paper, then tap the card to flip.

What is the formula that relates force to momentum?

force = change in momentum ÷ time


There are two ways you can write this using symbols.


F = tΔp​

 

F = tmv−mu​

Answer in your head, out loud, or on paper, then tap the card to flip.

Using the ideas of momentum and force, explain why car crashes can cause injury to the passengers.

When there is a car crash, the car and the passengers decelerate rapidly.


They experience large forces because of the very fast change in momentum - and these large forces can cause injuries.

Answer in your head, out loud, or on paper, then tap the card to flip.

Give 3 safety features of modern cars that reduce the risk of harm to passengers.

  1. Seat belts
  2. Air bags
  3. Crumple zones

Answer in your head, out loud, or on paper, then tap the card to flip.

How do seat belts work?

Seat belts stop you flying out of your seat during a car crash.


By stretching a little bit, they increase the time taken for the body's momentum to reach zero, and so reduce the forces on acting on the body.

Answer in your head, out loud, or on paper, then tap the card to flip.

How do air bags work?

Air bags provide a soft surface to collide with during a car crash.


By being flexible, they increase the time taken for the body's momentum to reach zero, and so reduce the forces acting on the body. 

Answer in your head, out loud, or on paper, then tap the card to flip.

How do crumple zones work?

Crumple zones are areas of a vehicle that are designed to crumple in a controlled way during in a collision.


By crumpling over time they increase the time taken for the passengers momentum to reach zero, and so reduce the forces acting on the bodies of the people in the car. 

Answer in your head, out loud, or on paper, then tap the card to flip.

What is the formula for impulse?

impulse = Δp = FΔt


impulse (kg ms-1)

Δ\Deltap = change in momentum (kg ms-1)

F = force (N)

Δ\Deltat = time force exerted (s)

Answer in your head, out loud, or on paper, then tap the card to flip.