## Motion

Remember that gravity =

**9.81 m/s^2**(it is acceleration)## Scalars and Vectors

**Scalar**- Something with

**only****magnitude**e.g. Speed, mass, temperature

**Vector**- Something with

**magnitude**e.g. velocity, current, acceleration

__and__direction**vector + vector = vector**

**scalar + scalar = scalar**

**vector x scalar = vector**

**scalar x scalar = vector**

**vector x vector = scalar**

## Resolving Vectors

When there are two vectors the overall vector can be calculated by a

**vector triangle**. This is done by actually**drawing**to scale the vectors involved. This enables you to work them out. To solve one of the vectors you need two of the other vectors in th vector triangle.## Kinematics

**Acceleration**- Rate of change of velocity

**Velocity**- Rate of change of displacement

**Displacement**- Distance in a certain direction

**Average Speed**- The average speed over a period of time

**Instantaneous Speed**- The speed at a certain point in time

## Displacement-time Graph

A positive gradient shows the object is moving forward

0 gradient shows the object is still

A negative gradient shows the object is returning back

The gradient gives the

__velocity__## Velocity-time Graph

A negative gradient shows the deceleration

The gradient gives the

__acceleration__## Linear Motion

__equations - equations of__

**'suvat'****constant acceleration**in a straight line

s = displacement (m)

u = initial velocity (m/s)

v = final velocity (m/s)

a = acceleration (m/s^2)

t = time (s)

## Galileo and Aristotle

Aristotle believed that the rate of fall was proportional to an objects mass. This meant that they accelerated at different rates.Galileo proposed that an object will fall at the same rate as an object of different mass. This can be shown in a vacuum. What actually affects the rate of fall is the surface area. Galileo proved this by dropping two cannon balls of different masses off the leaning tower of pisa. Although they didn't land at the same time he disproved Aristotle because using Aristotle's theory the two objects should have hit the floor much further apart in time |

## Gravity

As gravity is

An experiment to find it can be set up to discover what the magnitude of gravity is. A trap door and electromagnet method can be used.

**acceleration**caused by an objects gravitational energy.An experiment to find it can be set up to discover what the magnitude of gravity is. A trap door and electromagnet method can be used.

The acceleration over 's' can be discovered with the equation

This does have problems and in the exam they might ask you why.

**g = 2s/t^2**This does have problems and in the exam they might ask you why.

- If the electromagnet's
**current is too large**there will be a**delay**in letting the ball fall from the electromagnet after the current is switched off - If the distance is too large
**air resistance**might have an affect on acceleration - If the distance
**isn't accurately measured**this will drastically affect the result - The
**accuracy of the timer**also means that it's harder to get an accurate result