A cricket pitch is 20.12 m long. How long does light take to go from one end to the other?
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A cricket pitch is 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 , so that the old unit cancels. A prefix goes with the unit's power:
Time distance speed. Light travels ; sound in air about .
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.
Step 1. Light. .
Step 2. Sound. .
Answer: (a) . (b) .
Check. Sound is about a million times slower than light, and is indeed about times .
Watch out. To write seconds in nanoseconds, divide by (that is, multiply by ).
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