Physics, GCE O’ level. Definitions and formulae for relationships of variables.

1. General Physics.

Measurements.

While measuring, always place eye perpendicular to meter rule or meniscus reading to avoid parallax error.

Take multiple readings of quantities to minimize human perception time error and for better accuracy.

Kinematics

Average speed is the total distance covered by an object in a given time s=d/t. Velocity is the total displacement of an object in a given time. Acceleration is the change in Velocity (not speed) (∆v) in a specific time.

Acceleration due to free fall does not depend on mass, density or volume. All objects accelerate at the rate of 10m/s2 on earth.

Thus theoretically, feather and stone would fall to the ground at the same time, but due to air resistance and wind the feather will fall slower.

Air resistance is the force acting on a moving object, which opposes that movement. Air resistance increases with surface area of object, speed and the density of air.

A free falling object will accelerate, with the acceleration slowly decreasing with time. When the air resistance and the force of the falling object become equal and in opposite directions, the acceleration becomes zero and the object is said to be travelling at terminal velocity.

Forces

Newton’s first law of motion states that an object in motion or rest will not alter its state of motion or rest unless an external force is applied on it

Newton’s second law states that the magnitude of force acting on an object is the product of the mass of the object and its acceleration. F=MA

Newton’s third law of motion states that for every action involving force, there is an equal and opposite reaction.

Turning effects of forces.

The moment of a force is the product of the magnitude of force and the perpendicular distance from the pivotal point to the line of action of force.

Principal of moments: When a body is in dynamic equilibrium, the sum of clockwise moments and the...