A cricket pitch is 20.12 m long. How long does light take to go from one end to the other? …

Contributed by StemPy Lab

Try it on paper first. A hint, the key idea and the worked solution are here when you need them.

A cricket pitch is $20.12\ \text{m}$ long.

How long does light take to go from one end to the other? Give it in nanoseconds.
How long does the sound of the bat take? Give it in milliseconds.

Need a reminder? The key ideaShow

To change a unit, multiply by a fraction that equals one, such as $\dfrac{1000\ \text{m}}{1\ \text{km}}$ , so that the old unit cancels. A prefix goes with the unit's power:

\displaystyle 1\ \text{cm}^2 = (10^{-2}\ \text{m})^2 = 10^{-4}\ \text{m}^2, \qquad 1\ \text{cm}^3 = 10^{-6}\ \text{m}^3

Time $=$ distance $\div$ speed. Light travels $3.0 \times 10^{8}\ \text{m/s}$ ; sound in air about $340\ \text{m/s}$ .

The worked solution

Have you tried it?

Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.

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