Topic 1 Force & Motions

Speed

How fast you are going, measured in M/s, KM/H, or MPH.

Velocity

Speed in a specified direction, e.g., 30 mph north.

Average speed formula

Average speed = Distance ÷ Time taken.

Acceleration

How quickly the velocity changes, measured in M/s².

Equation relating final velocity (v), initial velocity (u), acceleration (a), and distance (s).

v² = u² + 2as

Distance time graph - Flat line

Indicates that the object is stopped.

Distance time graph - Steep line

Indicates that the object is moving fast.

Velocity time graph - Gradient

Represents acceleration.

First Law of Motion

An object at rest will remain at rest and an object in motion will remain in motion unless acted upon by a net external force.

Second Law of Motion

The acceleration of an object depends on the net force acting upon the object and its mass.

Resultant Force

The overall force acting on an object, calculated as Mass × Acceleration.

Third Law of Motion

For every action, there is an equal and opposite reaction.

Terminal Velocity

The constant speed an object reaches when the force of gravity is balanced by air resistance.

Hook's Law

Extension of a material is directly proportional to the force applied, until the elastic limit is reached.

Stopping distance formula

Stopping distance = Thinking distance + Braking distance.

Momentum

The product of an object's mass and velocity; a vector quantity.

Momentum conservation

Momentum before an event equals momentum after, provided no external forces act.

Center of gravity

The point where the weight of a body acts and hangs directly below the point of suspension.

Principle of moments

For an object to be balanced, total anticlockwise moments must equal total clockwise moments.

Vector quantity

A physical quantity that has both size and direction, such as force or velocity.

Scalar quantity

A physical quantity that has only size and no direction, such as mass or temperature.

Frictional force

A resistance force that increases with speed, affecting terminal velocity.

Elastic limit

The maximum extent to which a solid can be stretched without permanent deformation.

Driving factors of stopping distance

Factors include speed, reaction time, mass of car, braking quality, road conditions, and driver health.

Combining forces

To work out a resultant force, vectors must be added or subtracted.

Change in velocity

Can involve changes in speed, direction, or both.

Flat velocity time graph

Indicates steady speed.

Steep velocity time graph

Indicates greater acceleration or deceleration.

Area under a velocity time graph

Indicates distance covered.

Maximum moment

To achieve maximum moment, exert force perpendicular to the lever arm.

Balanced forces

When all acting forces cancel out, resulting in no change in motion.

Resulting moment

If total anticlockwise moments do not equal total clockwise moments, the object will turn.

Effects of mass on acceleration

Greater mass results in smaller acceleration for the same force used.