Physics - Forces and Motion (Speed, Friction, and Gravity)

Speed is a scalar quantity defined as the distance traveled per unit of time, measured in meters per second ($m/s$).

Average speed is calculated by taking the total distance traveled and dividing it by the total time taken: $v_{avg} = \frac{d_{total}}{t_{total}}$.

Friction is a contact force that opposes the motion of an object. It acts in the opposite direction to the direction of movement or intended movement.

Air resistance (drag) is a type of friction that occurs when an object moves through the air. It increases as the speed of the object increases.

Mass ($m$) is the amount of matter in an object and is measured in kilograms ($kg$). It remains constant regardless of location.

Weight ($W$) is the force of gravity acting on an object's mass, measured in Newtons ($N$). Weight changes depending on the gravitational field strength ($g$).

On Earth, the gravitational field strength ($g$) is approximately $9.8 \, N/kg$, though often rounded to $10 \, N/kg$ for IGCSE Grade 8 calculations.

A resultant force is the single force that has the same effect as all the forces acting on an object. If forces are balanced, the resultant force is $0 \, N$.