A stone may be skipped, by throwing it so obliquely that the water will cause it to bound off from its surface.
When a boat moves across a river at the rate of four miles an hour, and the current runs four miles an hour, in what direction will the boat go?
The boat will go diagonally across the river.
Why will the boat go diagonally across the river?
Because the boat will be carried as far down the river as the river is wide. If the river be one mile wide, then the boat, while crossing, will be carried down it one mile.
How do boatmen overcome this difficulty?
They overcome this by rowing the boat towards a point higher up the stream.
Does it take longer to cross a stream when the current is strong?
Yes; because the boat is carried farther down the stream by the current, and it must, therefore, go a greater distance in crossing.
Why is a person apt to fall when he jumps from a wagon that is moving?