Physics Forces and Motion

1. set up the apparatus

2. measure the length of the spring without any hanging masses

3. hang a mass of 100g on the spring

4. measure the new length of the spring

5. calculate the extension of the spring (the increased length)

6. repeat and increase the mass in increments of 100g

force is directly proportional to extension

if the graph has a linear region (straight line), then it obeys Hooke’s law

the ability of a material to recover its original shape after the forces causing deformation have been removed

mass x velocity

m x v

• you need to increase the time taken for a passenger to stop in a collision

• this is because force = change in momentum/time

momentum before the collision = momentum after the collision

change in momentum/time taken

mv-mu / t

whenever two bodies interact, the forces they exert on each other are equal and opposite

if object A exerts a force on object B, then object B exerts an equal and opposite force on object A

type and magnitude

force x perpendicular distance from the pivot

through its centre of gravity

when the clockwise moments are equal to the anti-clockwise moments a body will be in equillibrium

memorise

f1 x d1 + f3 x d3

• Clockwise moments = anticlockwise moments

• Moment = force x perpendicular distance from pivot

• If the the distance from the pivot is less on the left hand side it means that the force must be greater to compensate for the larger distance on the right hand side.

force x distance moved

f x d

energy transferred

mass x gravitational field strength x height

m x g x h

1/2 x mass x speed ^2

1/2 x m x v^2

because energy cannot be created or destroyed, the decrease in GPE = increase in KE for a falling object if no energy is lost to the surroundings.

the rate of transfer of energy or the rate of doing work

work done / time taken

w / t

distance moved / time taken

change in velocity/time taken

measure the gradeint

area underneath the graph

u² + 2 a x s

initial speed + 2 x acceleration x distance moved

electrostatic force is a force between objects that have an electric charge, gravitational force is a force between objects that have mass

electrostatic force can either be attractive or repulsive and is much greater than gravitational force

electrostatic force depends on the medium whereas gravitational force is independent of the medium

Vector quantities have magnitude and direction, like velocity. Scalar quantities have only magnitude, like speed.

a force that opposes motion

m x a

mass x gravitational field strength

thinking distance + braking distance

speed, alcohol, tiredness

icy road, worn tires, speed

As an object falls, air resistance increases until it equals gravity. At this point, the object stops accelerating and reaches a constant speed called terminal velocity.

As an object falls, air resistance increases until it equals gravity. at this point, the object stops accelerating and reaches a constant speed called terminal velocity