1. State an equation that links wave speed, distance and time.
2. Calculate the missing values in the table below.

3.   A wave travels at 1·5 m.s^-1. Calculate the time it will take to travel 30 m.

4.   Very high waves produced in the ocean due to earthquakes are called tsunamis. A tsunami travelled from Sumatra to Somalia, a distance of 6000 km, in 7 hours. Calculate the speed of this wave in metres per second.

5.   How long would it take a sound wave to travel from one end of a football pitch to the other if it is 105 m long? (Speed of sound in air is 340 m.s^-1).

6.   A surfer rides along the crest of a wave for a distance of 48 m in 12 s. Calculate their speed.

7.   Light travels through space at 3 X 10⁸ m .

(a)   The moon is 3·8 X 10⁸ m from Earth. Calculate the time it will take for light reflected from the moon to reach Earth.

(b)   The Sun is an average of is 1·5 X 10¹¹ m from the Earth. Calculate the time it will take for light from the Sun to reach Earth.