Speed

Formula for speed

• The formula for speed is distance equals speed times time
• This can be drawn as a triangle

Using a formula triangle

• Cover up the quantity you want to find with your finger
• The position of the other two quantities tells you the formula

Units

• The most common units of speed are
    * metres per second
    * kilometres per hour
    * miles per hour
• To convert between measures of speed you need to convert one unit firs then the other
• Write the new units at each step of your working

Minutes and hours

• For questions on speed, you need to be able to convert between minutes and hours
• Remember there are 60 minutes in 1 hour
• To convert from hours to minutes you multiply by 60

Speed checklist

• Draw formula triangle
• Make sure units match
• Give units with answer

Typical speeds

• When people walk, run, or travel in a car their speed will change. They may speed up, slow down or pause for traffic. The speed at which a person can walk, run or cycle depends on many factors including:

• age

• terrain

• fitness

• distance travelled

• It is not only moving objects whose speed can vary. The speed of the wind and the speed of sound also vary.
    * A typical value for the speed of sound in air is about 330 m/s.

• The velocity of an object is its speed in a particular direction. Velocity is a vector quantity because it has both a magnitude and an associated direction.

• To calculate velocity, displacement is used in calculations, rather than distance.

• Unlike distance, which is a scalar quantity, displacement is a vector quantity. It includes:

• the distance travelled, measured in a straight line from start to finish
    * the direction of the straight line