Forces and Motion in Edexcel IGCSE Physics

Scalar Quantity

A scalar quantity is a magnitude. It can be described fully with a single numerical value. Ex: distance, speed, time, mass, energy.

Vector Quantity

A vector quantity has both a magnitude and a direction. Ex: Force, velocity, displacement, momentum, moment.

Gradient of a distance-time graph

The property of a distance-time graph that can be used to calculate speed.

Distance-time graph states

A = constant speed, B = at rest, C = accelerating.

Average Speed Equation

Average speed(m/s) = Distance(m) / Time(s) v=d/t.

Acceleration Definition

Acceleration is the change in velocity per unit of time. SI Unit: m/s².

Acceleration Equation

Acceleration = (Change in velocity) / time a = (v-u) / t, where v is final velocity and u is initial velocity.

Gradient of a velocity-time graph

The property of a velocity-time graph that can be used to calculate acceleration.

Area under the velocity-time graph

The property of a velocity-time graph that can be used to calculate distance travelled.

Velocity-time graph states

A = constant speed, B = accelerating, C = decelerating.

Final Speed Equation

An equation linking final speed, initial speed, acceleration and distance travelled.

Types of Forces

A = weight, B = Air Resistance (Drag).

Forces opposing motion

1. Friction, 2. Air Resistance (Drag).

Force holding planets around the Sun

Gravitational force.

Gravitational Force

The force that holds planets around the Sun.

Electrostatic Force

The force that holds electrons around the nucleus.

Ways a force can affect an object

It can change the shape of the object (extension/compression), change the speed of the object, or change the direction the object is moving.

Resultant Force Example A

5N to right.

Resultant Force Example B

0N (balanced).

Resultant Force Example C

13N downwards.

Magnitude of Resultant Force

10N, 50N, 5N, 10N.

Magnitude of Resultant Force

45N.

Equation linking unbalanced force, mass and acceleration

Force (N) = Mass(kg) x Acceleration (m/s²) or F = m x a.

Equation linking mass, weight and gravitational acceleration

Weight(N) = Mass(kg) x g (m/s²) or W = mg.

Stopping Distance Relationship

Stopping Dist. = Thinking Dist. + Braking Dist.

Factors affecting stopping distance of a car

Reaction time, Weather conditions, Initial speed, Driver's conditions, Road Conditions, Mass of the car, Tire Conditions.

Factors affecting air resistance on a falling object

Surface Area and Speed.

Terminal Velocity Description

A falling object accelerates under its weight until air resistance increases to balance the weight, resulting in zero acceleration and reaching terminal velocity.

Hooke's Law

Extension is directly proportional to the force applied.

Elastic Behavior

In elastic behaviour, an object recovers its original shape when the forces causing the extension are removed.

Plastic Behavior

In plastic behavior, there is a permanent deformation to the shape of the object when forces are removed.