Forces, Motions and Energy

When the resultant force has equal amount of force on both sides of an object the object is stationary. 

If there is a bigger force on one side you can find the newton by subtracting one side from the other force you are trying to find. So if there was 10N force on the left side and 20N force on the right then the overall force would be 10N to the right.

If an object is moving, a car for example there is air resistance and friction pulling the car back and the acceleration force infront.Work out the resultant force in the same way. For a MOVING object

If the Resultant force = 0 than the car is a steady speed.

If the resultant for is NOT 0 than the object accelerates in the given direction.

velocity- how far something is moving in a certain direction 

speed= distance/time 

acceleration= final velocity - initail velocity/ time (a= u-v/t)

acceleration unit is m/s2 (metres per second squared)

negative acceleration is the same as slowing down. aka deceleration 

velocity time graph - distance = area under the graph

a = f/m acceleration= force (resultant)/ mass

Terminal velocity is to do with objects falling through fluids. (liquid or gas)

1. weight pulling down and air resistance in the opposite direciton, so the acceleration is downwards.

2. accelerating less 

3. forces become balance so the object is falling at a steady speed this is know as terminal velocity.

4. when a parachute opens the upward force increaser causing the object to slow down

5. force balance out again, slower terminal velocity.

also should know how to interpret this on a graph

Streching the spring means work has been done. Work means that energy has been transferred, giving the spring elastic potential energy.

Hooke's Law-

The extention of an elastic object is directionally proportional to the force applied, given that the limit of proprtionality is not exceeded. (over streched)

mass and force are not the same

f = k x e   force = spring constant x extention

work is measured in joules 

work= force x distance

power = work done / time taken

power is measures in watts 

kinetic and gravational potentioal is a type of energy. Kinetic is movement. Gravitational potentional the amont something is about the ground.

kinetic energy = 1/2 x mass x velocity2 squared.

change in gravitational potentional energy= mass x gravitational field strength x height

gravitational field strength of earth is 10N/kg

Wieght is a force measured in Newtons, weight is measured downwards towards the centre of the earch. 

Mass is measures in kg, weight in Newtons 

Weight = mass x gravitational field strength      (w =m x g)