Bafana

The depth of a body of water can be found by emitting sound pulses reflected from the bottom. If the time interval from emission to detection is 2 s, what is the depth of the water? The correct answer is 1498 m. How do I get it?

A girl of mass 50kg runs up a flight of stairs.After 10 minutes she is 250 metres above the ground. Determine her average power output. Ignore the effects of friction.

A flying bat emits squeaks at a frequency of 80 MHz, if a stationary observer picks up the frequency of the squeaks as 78 MHz, is the bat moving towards or away from the listener? Determine the speed of the bat.