Momentum

Question 0

Momentum equation

Answer 0

Momentum = mass x velocity 
(kgm/s) = (kg) x (m/s)
p = m x v

Question 1

Momentum is a … Quantity

Answer 1

Vector

Which means it has direction and magnitude

Question 2

A minus sign in momentum

Answer 2

Shows the direction of the object

Question 3

What is a vector quantity

Answer 3

Something with direction and magnitude

Question 4

State the conservation of momentum

Answer 4

The sum of the momentum before q collision (or explosion) is equal to the sum of the momentum after, providing there are no external forces acting on the system

Question 5

conservation of momentum equation

Answer 5

(Sum)Pbefore = (sum) Pafter
Therefore
MaVa + MbVb = Ma+b x V

Question 6

Under what conditions is momentum not conserved

Answer 6

If there are no external forces acting on the system, like friction

Question 7

Forces are required to increase or decrease the … Of an object

Answer 7

Momentum

Question 8

3 main car safety requirements

Answer 8

Air bags
Seat belts
Crumple zones

Question 9

Force and momentum equation

Answer 9

Force = change in momentum/time for change
Therefore
F = pv - pu /t

Question 10

Explain how an airbag works

Answer 10

The inflation of an airbag after a crash inflates which increases collision time. The change in momentum stays the same as it is fixed. The force acting upon the person therefore decreases. Once the person had been slowed down by the airbag, it deflates to avoid suffocation.

Question 11

When answering questions on car safety, always include:

Answer 11

• change in momentum during a crash is fixed
• f = p(v - u) /t
• time for collision is increased by the device
• resulting in the impact force, F being decreased

Question 12

How do rockets take off?

Answer 12

• total momentum before and after is zero
• this means momentum of rocket and gases are equal (acting in opposite direction)
• the rocket has a much greater mass than the gases
• therefore the gases move at a very fast velocity which causes rocket to take off

Question 14

What do crumple zones do

Answer 14

• Increase the amount of collision time
• reducing the amount of force acting upon the passenger safety cell (a rigid cage to prevent the roof from collapsing onto passengers / driver)
• the crumple zone is designed to dissipate the energy from a collision thus slowing the acceleration of the car

Question 15

moment and distance (from pivot) equation

Answer 15

m = f x d

Question 16

clockwise and anticlockwise moment

Answer 16

(sum)Mc = (sum)Mac