A crane lifts four pallets of bricks, each of which weigh 5000 N. The crane lifts each pallet a height of 30m. The crane takes 4 minutes to do this.
How much useful power did the crane produce to lift the bricks?

A.150 000 W

B.625 W

C.2500 W

D.37 500 W

Astudent is working in a lab to determine how time affects impulse. the student keeps the force the same in each trial but changes the impact time. some data is shown.

Explain the comparisons between nature and packingtown that appears on pages 81 and 82 answer

Consider an insulating crystal, made up of layers of atoms. what form would you expect the temperature dependence of the phonon heat capacity to approach at extremely low temperatures if the interlayer coupling is i)very strong (rigid coupling), and ii) very weak. explain.