# Definitions and Info Physics IGCSE

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• Created by: JulieP123
• Created on: 12-01-19 10:58

First law of motion: Balanced forces mean no change in velocity. So long as the forces on an object are all balanced, then it'll just stay still, or else if it's already moving it'll just carry on at the same velocity - so long as the forces are balanced

Second law of motion: A resultant force means acceleration. If there is an unbalanced force, then the object will accelerate in that direction

Third law of motion: Reaction forces. If an object exerts a force on another object then an equal and opposite force is exerted back.

Vector quantity- has size and direction. e.g. force, velocity, acceleration, momentum, e.c.t.

Scalar quantity- only has size. e.g. mass, temperature, time, length, e.c.t.

Hooke's law says that extension is proportional to the force

Thinking Distance- The distance the car travels in the time between the driver noticing the hazard and applying brakes. it is affected by the speed you are going and. your reaction time is affected by tiredness, drugs, alcohol, old age, inexperience.

Braking Distance- The distance the car travels during its deceleration whilst the brakes are being applied. It is affected by how fast you are going, the mass of the vehicle, how good the brakes are and the grip (road surface, weather, tyres)

Stopping distance = thinking distance + braking distance

How cars are built to affect stopping distance: Crumple zones crumple on impact, increasing the time taken for the car to stop. Seat belts stretch slightly, increasing…