Motion 2

Equations of Uniformly Accelerated Motion

When we have objects moving with a constant acceleration we can also use certain equations to solve problems. In these equations we use the following symbols:

You should be able to recall ALL of the following equations:

This implies that

The above equation can be rewritten as:

You should also know ALL of the following:

Falling Objects

We can drop a large stone and a piece of chalk from a height of 3 or 4 metres and they land simultaneously. However, a stone will reach the ground faster than a piece of paper. If the stone and paper are allowed to fall in a vacuum they fall together.

When objects fall in the air the resistance of the air has a greater effect on the light objects, such as the paper, than on heavy ones, such as the stone. Fluid friction (or viscous drag) always opposes the fall of objects through fluids, i.e. liquids and gases.

Acceleration due to Gravity

If the effects of air resistance are eliminated, or negligible, then all objects fall with the same acceleration. This is called acceleration due to gravity, g.

The acceleration due to gravity has slightly different values in different parts of the world but all values are about 9.81 metres per second squared. We often take g as 10 metres per second squared, as a convenient approximation.