Momentum Energy Work And Power

Question 1

What factors effect thinking distance

Answer 1

Reaction time - this is effected by drugs alcohol and age

How fast your going

Question 2

What effects braking distance

Answer 2

How fast your going

The mass of the vehicle - a heavier vehicle will take longer to stop

How good the brakes are

How good the grip is - road surface weather conditions and tyres

Question 3

What is the stopping distance of a car

Answer 3

The distance covered in time between the driver first spotting a hazard and the car coming to a complete stop

Question 4

Momentum =

Answer 4

Mass x velocity

Question 5

What is momentum

Answer 5

The greater the mass of an object and the greater the velocity the greater the momentum
It is a vector and has a size and a direction

Question 6

What is conservation of momentum

Answer 6

Total momentum before is equal to the total momentum after

Question 7

Force (N) =

Answer 7

Change in momentum / time

Question 8

How does force effect momentum

Answer 8

A larger force means a faster change of momentum

Question 9

What protective features do cars have to decrease the impact of crashes

Answer 9

Crumple zones crumple on impact which increases the time it takes the car to stop therefor decreasing the impact

Seat belts stretch slightly which increases the time taken for the person to stop which reduces the forces acting on the chest

Air bags help the person to slow down more quickly

Question 10

How are eggs used to show the effect of crumple zones

Answer 10

Dropping an egg on a hard floor will cause it to smash streicht away but if you create a crumple zone on the egg like a soft cushion or bubble wrap it won’t crack with the impact

Question 11

What does work done mean

Answer 11

When a force moves an object energy is transferred and work is done
When something moves something else is providing the energy for it to move the thing moving the object does the work by transferring energy

Question 12

Work done =

Answer 12

Force X distance moved in the direction of the force

Question 13

Power =

Answer 13

Work done / time taken

Question 14

What is power

Answer 14

The amount of energy transferred in a space of time
It is measured in watts
Watts are joules per second

Question 15

What is kinetic energy

Answer 15

Anything moving has kinetic energy
It depends on mass and velocity the more something weighs and the faster it is going the bigger the kinetic energy will be

Question 16

Kinetic energy =

Answer 16

1/2 X mass X velocity ^2

Question 17

How does a car stop

Answer 17

The kinetic energy must be converted to heat energy in the brakes and tyres

Kinetic energy = work done by brakes to stop the vehicle (force x distance)

Question 18

What is gravitational potential energy

Answer 18

The energy that is created by height that gives the object a power to fall

Question 19

Gravitational potential energy =

Answer 19

Mass X height X gravitational field strength

Question 20

What is the principle of conservation of energy

Answer 20

Energy can never be created or destroyed only transferred from one form to another

Energy is only useful when transferred from one form to another

Question 21

What happens when an object falls

Answer 21

When something falls it’s gpe is converted to kinetic energy so the further it falls the faster it goes

Kinetic energy gained = gpe lost

Question 22

Why is energy lost as heat

Answer 22

Heat is transferred to cooler surrounding S so they become warmer so the energy becomes less concentrated the energy is still there but it can’t be used again