Forces and motion

gradient is velocity
horizontal line means object is stationary
curved line means object is accelrating
Velocity-time graph

Gradient is accleration
horizontal line means constant speed
area under the line is the distance travelled
curved line means acceleration is changing

Average speed = total distance/total time
v = d/t

final velocity-initial velocity/time
(v-u/t)

Final speed squared = initial speed squared + (2 x acceleration x distance moved)
v^2 = u^2 + 2as

a quantity that has both magnitude and direction, speed
a quantity that only has a magnitude, velocity, force

Balanced forces mean the object has a constant velocity

resultant force means acceleration F=ma

For every action there is an equal and opposite reaction

mass is a measure of how much matter is in an object, weight is a gravitational force

Force = mass x acceleration
(F = ma)

Weight = mass x gravitational field strength
(W=mg)

As the object falls there is no air resistance/drag acting on it and the only force acting is weight (downwards)
As it falls, it accedlerates which incereases its speed hence air resistane
This causes the resultant foce downwards to decrease
Therefore, acceleration decreases
Eventuallly both the forces are balanced so there is no resultant force
No acceleration means terminal velocity reached

The distance travelled by a vehicle from when the driver notices the hazard and applies the brakes

the distance a car travels from the time the driver applies the brakes until the car comes to a complete stop

Greater speed
Slower reaction time (alcohol, sleep, tiredness)

- Greater speed
- Greater mass
- Poor road conditions (icy wet- less friction between road and tires
- Poor brake and tires condition (worn)

Extension is directly proportional to the force applied until the spring reaches it's elastic limit

Moment = Force x perpendicular distance from pivot
Moment = Fd

The sum of the clockwise moments is equal to the sum of the anticlockwise moments when object is balanced

momentum = mass x velocity
p = m x v

Force = change in momentum / time taken
F = mv - mu/t

iF the object is in the middle both ends will be applying the same force. If the object is moved towards the right end, the force being applied by the right end will increase so it can balance out the moment applied by the box around the left end. The further away the object is from the left end the greater force applied by the right end