Pick the best description of energy efficiency? a efficiency is equal to the ratio of energy you put into the energy you get out b efficiency is equal to the ratio of energy you get out to the energy you put in c efficiency is equal to the sum of the energy you put into the energy you get out

Is there a point between a 10 nc charge and a 20 nc charge at which the electric field is zero?

Aballoon is rising vertically upwards at a velocity of 10m/s. when it is at a height of 45m from the ground, a parachute bails out from it. after 3s he opens his parachute and decelerates ata a constant rate 5m/s.when. (a) what was the height of the parachutist above the ground when he opened his parachute? (b)how far is the parachutist from the balloon at t=3s? (c)with what velocity does the parachutist hit the ground? (d)after how long does the parachutist hit the ground after his exist from the balloon?

Which of the following examples illustrates static friction? a box sits stationary on a ramp. a ball rolling on the lawn eventually comes to rest. a car rounds a curve on a road. a fish swims upstream.