Section 14 Work Power and Energy More Power

Section 14 Work, Power, and Energy

More Power!!!!! What does he mean?

Work is the product of force and distance § For a force to do work on an object, the object must move in the same direction of the force § Any force that does not act in the direction of the motion is not doing work

Work Equation Work can be calculated by the following equation: Work = Force x Distance W = F (Newtons) x D (Meters) The SI unit for work is Joules

Work Equation Example #1 How much work is done when raising a 1600 N barbell 2 meters?

Work Equation Example #2 How much work is done when pushing a box with 234 N of force and moving that box 40 meters?

Power is the rate of doing work To increase power, you need to do more work in the same amount of time, or do the same amount of work in less time

Power Equation Power = Work (Joules) Time (seconds) The SI unit for power is watts

Example Problems Example #3 If 45 J of work are done in 120 seconds how much power is used?

Example Problems Example #4 You exert a vertical force of 72 Newton's to lift a box to a height of 1. 0 meter in a time of 2. 0 seconds. How much power is used to lift the box?

14. 1 Assessment Question #1 What conditions must exist in order for a force to do work on an object? Force must act in the same direction as the object moves

14. 1 Assessment Question #2 What formula relates work and power? Power = Work / Time

14. 1 Assessment Question #3 A desk exerts an upward force to support a computer resting on it. Does this force do work? Explain. The force does no work because it acts on the computer, but it does not move, therefore no work is done.

14. 1 Assessment Question #4 How much work does a 25 N force do to lift a potted plant from the floor to a shelf 1. 5 meters high? Work = 37. 5 joules

14. 1 Assessment Question #5 You 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? Power = 50 Watts