Energy
Define energy
The ability to do work
Define Work
The transfer of energy by an application of force
Define Power
the amount of energy transferred or converted per unit time.
A device that makes work easier
SI unit for Energy
Joules (J)
Kinetic/Mechanical
A couch is pushed with a force of 75 N and moves a distance of 5 m across the floor. How much work is done in moving the couch?
375J
In lifting a baby from a crib, 50 J of work are done. How much power is needed it the baby is lifted in 2.0 s?
2.0W
True or false: A simple machine can magnify the force
True
Si Unit for distance
m
How much gravitational potential energy would a 60 kg person gain if they climb to the top of a tree that was 15 m
high?
8,820J
A car travels a distance of 50 m while exerting a force of 4,800 N. How much work did the car do?
240,000J
The power produced by an electric motor is 500 W. How long will it take the motor to do 10,000 J of work?
20s
The student uses the scissors to cut a piece of paper. identify the work output in this scenario?
The scissors
Si unit for work
Joules (J)
An object has a mass of 24 kg and a velocity of 15 m/s. How much kinetic energy does the object contain?
2700J
You throw a ball with a horizontal force of 4.2 N, which performs 6.1 J of work on the ball. How far does the ball travel?
1.45m
If a runner’s power is 130 W as she runs, how much work is done by the runner in 600 s?
78000J
Which is greater, the work input or the work output?
neither, they are the same
Si unit for time
Seconds (s)
fuel is an example of __________
Chemical Potential Energy
Work is dependent upon____ and ______
Force and distance
If You exert 500 N of force to move a heavy desk a distance of 3.0 meters. How much power would you need to exert to move the desk in 2.0 seconds?
750W
List all 6 simple machine categories
Lever, Pulley, incline plane, wedge, screw, wheel and axle
Si Unit for Power
Watts (W)