. A boy hears the echo of his own voice from a distance hill after 0.8 seconds . If the speed of sound in air is 340m/s, calculate the distance of the hill from the boy?

A1000-kg weather rocket is launched straight up. the rocket motor provides a constant acceleration for 16-s, then the motor stops. the rocket altitude 20-s after launch is 510-m. you can ignore any effects of air resistance. a. what was the rocket’s acceleration during the first 16-s? b. what is the rocket’s speed as it passes through a cloud 5100-m above the ground?

In a voltaic cell, electrons flow from the (positive/negative) to the (positive/negative) terminal.

What do you think car designers do if the damage caused by a crash test is too severe?