Time to Practice
Skyler uses 30 N of force to push a grocery cart 100 meters. How much work does she do?
W =Fd 300 N x 100 meters = 3,000 J
Roy uses 15 N of force to push a box 15 meters across a room. How much work did he do?
W = Fd 15 N x 15 m = 225 J
A 50 N child climbs a 5 meter slide. How much work is done by the child?
W = Fd 50 N x 5 m = 250 J
Rylee does 45 J of work to push a felt marker 3 meters. How much force did she use?
F = W/d 45 J / 3 m = 15 N
Sherry uses a force of 25 Newtons to lift her suitcase while doing 75 Joules of work. How far did she lift her suitcase?
d = w/F 75 J/25 N = 3 meters
A lighting fixture, with 4 bulbs, each using 500 J of electrical power burn for 20 s. What is the wattage (power) of all four light bulbs?
P = w/t 500 x 4 = 2000/20 s = 100 watts
If you did 100 J of work in 5 seconds, what was your power output?
P = w/t 100 J / 5 s = 20 watts
A deflated hot air balloon weighs a total of 8000 N. Filled with hot air, the balloon rises to a height of 1000 meters. How much work is accomplished by the hot air?
W = Fd 8000 x 1000 = 8,000,000 J
Shea Weber, of the Nashville Predators, slaps a hockey puck with 2493 Joules of work when he shoots to score a goal that is 10 meters away. How much force did Shea use to hit the puck?
F=W/d 2493 J/10 m = N
If it takes you 20 seconds to do 800 J of work on a box of books to move them up an inclined plane, what is your power output?
Power = work/time 800 J / 20 s = 40 watts