# Mechanics

## What to expect

Mechanics is the study of the interactions between physical bodies and their consequent motion.

After studying this topic, you should be able to: ## Key questions

#### What are the types of motion graphs?

Motion graphs come in two main formats: displacement vs time (gradient is velocity) and velocity vs time (gradient is acceleration and area is displacement). Find out more.

#### How do you use the equations of motion?

To solve problems using the equations of motion, annotate the question with the three quantities that are provided (e.g. u, a and t) then select the equation that includes these and the desired quantity (e.g. v). Rearrange, substitute and solve. Find out more.

#### What are examples of forces?

Normal reaction, weight, tension, friction and drag are some examples of forces. Find out more.

#### What are Newton's 1st, 2nd and 3rd laws?

Newton's 1st law states that an object will remain at rest or at constant velocity unless acted upon by a resultant force. Find out more.

Newton's 2nd law states that the rate of change of a momentum of a body is proportional to the resultant force and is in the same direction as the force. Find out more.

Newton's 3rd law states that if body A exerts a force on body B, body B exerts an equal and opposite force on body A. Find out more.

#### How do we define power in physics?

Power is defined as the rate at which work is done. Find out more.

#### What happens to momentum when cars collide?

Momentum is a quantity that is conserved. This means that the total amount is constant throughout an interaction, such as a collision, provided that there are no external forces acting. Find out more.

• ### Kinematics

Kinematics is the study of moving objects.

• ### Forces

Every new movement, direction, squash or stretch requires a force.

• ### Work and energy

Work done and energy changed are equivalent.