Presentation on theme: "Work and Power 1. Describe the conditions that must exist"— Presentation transcript:
1Work and Power 1. Describe the conditions that must exist for a force to do work on an object.2. Calculate the work done on an object.3. Describe and calculate power.
2What is Work? Work is the product of force and distance. Work requires motion. If there is no movement then no work is done.The force must act in the same direction as the object moves. Any part of a force that does not act in the direction of motion does no work on an object.
4Units of WorkThe Joule (J) is the SI unit of work. It is the work of moving an object with the force of 1 Newton to a distance of 1 meter.
5Practice using the Work Formula A weight lifter lifts a 1600 N barbell over his head 2.0 meters high.W = F x DW = 1600 N x 2.0 mW = 3200 J
6What is PowerPower is the rate of doing work. Doing work at a faster rate requires more power.To increase power:1. increase the amount of work done in a given time2. do a give amount of work in less time.
8Units of PowerThe SI unit of power is the watt (W), which is equal to one joule per second.
9How much work does a 25-newton force do to lift a potted plant from the floor to a shelf 1.5 meters high?52 J48 J24 J38 J1234567891011121314151617181920212223242526272829303132
10You lift a large bag of flour from the floor to a 1-meter-high counter, doing 100 joules of work in 2 seconds. How much power do you use to lift the bag of flour?50 W52 W48 W42 W1234567891011121314151617181920212223242526272829303132
11In which of the following cases is work done on an object? Pushing against a locked door.Suspending a heavy weight with a strong chain.Pulling a trailer up a hill.Carrying a box down a corridor.1234567891011121314151617181920212223242526272829303132