If you check your electricity bill, you will note that you are paying the power company for so many kilowatt-hours (kWh). Are you really paying for power? Explain.
Answer to relevant Questions(a) Does efficiency describe how fast work is done? Explain. (b) Does a more powerful machine always per-form more work than a less powerful one? Explain. You want to decrease the kinetic energy of an object as much as you can. You can do so by either reducing the mass by half or reducing the speed by half. Which option should you pick, and why? A500-kg, light-weight helicopter ascends from the ground with an acceleration of 2.00 m/s2. Over a 5.00-s interval, what is (a) The work done by the lifting force, (b) The work done by the gravitational force, and (c) The ...A certain amount of work is required to stretch a spring from its equilibrium position. (a) If twice the work is performed on the spring, the spring will stretch more by a factor of (1) √2 (2) 2, (3) 1√2 (4) 1/2. Why? ...A 1200-kg automobile travels at 90 km/h. (a) What is its kinetic energy? (b) What net work would be required to bring it to a stop?
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