Newton’s 2nd Law

Newton’s 2nd Law states:

When an unbalanced force acts on an object it produces an acceleration that is:

• Directly proportional to the force, and
• Indirectly proportional to the mass of the object

Or stated another way: the acceleration of an object increases as the applied force increases and decreases as the mass of the object increases.

Newton’s 2nd Law can be expressed:

Where:

= force in Newtons

= mass in kilograms

= acceleration in

The unit for force, the Newton is the force required to accelerate a mass of  at

Example 1:

A  500kg bike is accelerated at 1.5 . Calculate the force acting on the bike:

Using

Some questions will require the original equation to be rearranged:

Example 2:

A 2kg ball is accelerated by a force of 15N acting to the right. Calculate the acceleration of the ball:

Using

to the right

Some questions will use a mass that is not in kg. The mass needs to be converted to kg for the calculation to be in the correct units:

Example 3:

Calculate the force acting on a 200gm toy that accelerates to the left at 2.4 :

Using

to the left