Answer:
leverage
Explanation:
Leverage ...this allows you to use less force through a longer distance
When you shine a lite through a prism is reflects out light through all of the edges and causes light separation. Or just simply shine a laser through the edge of a sideways piece of glass.
I hope that this was helpful for you.
20m away
the dog was 60m away from. you subtract 40m since it is 10m/s x 4 seconds