How much energy is dissipated as heat during a two-minute time interval by a 1.5- kω resistor which has a constant 20- v potential difference across its leads?

When you drop a pebble from height a it reaches the ground with speed v if there is no air resistance. from what height should you drop it so it will reach the ground with three times the speed? (a) 9m (b) 3m (c) 6m (d) 18m

Which simple machine is not part of this compound machine? a. lever b. pulley c. inclined plane d. wheel and axle

Aboy with a mass 25 kg climbs into a small tree. he sits on a branch that is 2.o m above to the ground.what is his gravitational potential energy above the ground?