A small hydroelectric power station diverts water from a river. Every second, 20kg of water flows through a pipe and falls through a vertical drop of 15m. The efficiency of the power station is 0.60 (60%). The gravitational field strength g is 10N/kg. What is the power output?

A parachutist has opened his parachute and is falling to Earth at constant speed. What is the principal energy conver…

A small emergency generator supplies 432 000 000 J of electrical energy in twenty-four hours. What is the average pow…

Which quantity is measured in kilowatt-hours?

Which row correctly compares the speeds of sound in air, liquid and solid?

A guitar string is made to vibrate. What makes the pitch of the note rise?

A teacher sticks a magnet to the top surface of a match-box cover. The bottom surface is placed in a small tray of ir…