# Physics - As Fast As You Can

A set of revision cards explaining simple physics formulas.

HideShow resource information
• Created by: Elliza
• Created on: 29-05-11 22:14

## Speed and Velocity

To work out velocity, speed, displacement or time taken, use this:

• The 'D' represents 'Displacement'
• The 'S' represents 'Velocity' or 'Speed' (Both calculations are the same in this case)
• The 'T' represents 'Time'

Bear in mind that 'm/s' (metres per second) is used for both, speed and velocity. (E.g 40 m/s) However, velocity is a vector quantity, which means it also needs a direction. (E.g 40 m/s North)

1 of 4

## Acceleration

Acceleration is how quickly velocity is changing.

The unit for acceleration is m/s².

To work out acceleration use this:

In order to work out the change in velocity, you need to use this:

Change in velocity = Finishing velocity (m/s) - Initial velocity (m/s)

For example, A skulking cat accelerated from 2m/s to 6m/s in 5.6s. Find it's acceleration.

Answer: Using the formula

Acceleration = (v - u) / t = (6 - 2) / 5.6 = 4 / 5.6 = 0.71 m/s²

'V' represents the finishing velocity, 'U' represents the initial velocity.

2 of 4

## Velocity Time Graphs

Here is a typical velocity time graph:

3 of 4

## Velocity Time Graphs Continued...

Things to remember about velocity time graphs:

• Gradient = Acceleration
• Flat sections represent steady speed
• The steeper the graph, the greater the acceleration or deceleration
• Uphill sections (/) are acceleration
• Downhill sections (\) are deceleration
• The area under any section is the distance travelled in that time interval
• curve means changing acceleration.

4 of 4