SPH301 Lesson 06 Energy Using the formula for power: At Substitute in the formula for Work. You will notice that power can be expressed as a force multiplied by another quantity (look at the remaining terms to determine that quantity). Write the alternate formula for power: EXAMPLE 1 If a car engine does 25,000 kJ of work over 12 s to climb a hill, calculate the average power of the engine. (2.1 x 10 W) EXAMPLE 2 A 90 KW motor exerts an average force of 4.0 KN to move a speedboat at a constant speed through the water. How fast, in km/h, is the boat moving? (81 km/h) EXAMPLE 3 A snow tubing lift pulls riders up a 120 m long hill at a constant speed. The hill makes an angle of 220 to the horizontal and there is 145 N of friction between the tubes and the snow. The rider is 55 kg. and it takes 30.0 s to get up the hill. Sketch a labeled diagram: a) How much work does friction do? b) What will be the gain in the rider's gravitational potential energy? c) How much work will the lift need to do