# P2.1 Forces and their effects

Mind Map by Shannon R, updated more than 1 year ago
 Created by Shannon R over 6 years ago
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Physics AQA

## Resource summary

P2.1 Forces and their effects
1. Resultant forces
1. When two object interact, they always exert an equal and opposite force to each other.
1. The resultant force is one single force that replaces the effect of all the forces acting on an object
1. A resultant force acting on an object may cause a change in its state or motion
2. If the resultant force acting on the object is zero then the object will not move.
3. Forces and motion
1. F = ma
1. The gradient of a distance-time graph represents speed
1. The velocity of an object is its speed in a given direction
1. a = v-u/t
1. The gradient of a velocity- time graph represents acceleration
2. Forces and braking
1. When a vehicle travels at a steady speed the resistive forces balance the driving force.
1. The greater the speed of a vehicle the great the braking force needed to stop it in a certain distance.
1. The stopping distance of a vehicle is the sum of the distance the vehicle travels during the driver's reaction time (thinking distance) and the distance it travels under the braking force (braking distance)
1. A driver's reaction time can be affected by tiredness, drugs and alcohol
1. When the brakes of a vehicle are applied, work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increase
1. A vehicle's braking distance can be affected by adverse road and weather conditions and poor condition of the vehicle
2. Forces and elasticity
1. A force acting on an object may cause a change in shape of the object
1. A force applied to an elastic object such as a spring will result in the object stretching and storing elastic potential energy.
1. For an object that is able to recover its original shape, elastic potential energy is stored in the object when work is done on the object to change its shape.
1. F = k * e
2. Forces and Terminal Velocity
1. The faster an object moves through a fluid the greater the frictional force that acts on it
1. An object falling through a fluid will initially accelerate due to the force of gravity. Eventually the resultant force will be zero and the object will move at its terminal velocity.
1. Calculate the weight of an object using the force exerted on it by gravitational force: W = m * g