What is the cost of operating a 3.00-W electric clock for a year if the cost of electricity is ?
|Distance traveled with rocket engine firing (m)||Payload final velocity (m/s)|
A 1.0 kg baseball is flying at 10 m/s. How much kinetic energy does it have? Potential energy?
10 J, 20 J
50 J, 20 J
unknown, 50 J
50 J, unknown
You are loading a toy dart gun, which has two settings, the more powerful with the spring compressed twice as far as the lower setting. If it takes 5.0 J of work to compress the dart gun to the lower setting, how much work does it take for the higher setting?
Old-fashioned pendulum clocks are powered by masses that need to be wound back to the top of the clock about once a week to counteract energy lost due to friction and to the chimes. One particular clock has three masses: 4.0 kg, 4.0 kg, and 6.0 kg. They can drop 1.3 meters. How much energy does the clock use in a week?
Old-fashioned pocket watches needed to be wound daily so they wouldn’t run down and lose time, due to the friction in the internal components. This required a large number of turns of the winding key, but not much force per turn, and it was possible to overwind and break the watch. How was the energy stored?
A small mass raised a long distance
A large mass raised a short distance
A weak spring deformed a long way
A strong spring deformed a short way
Across the rug is 275 J extra
Around the floor is 5 J extra
Across the rug is 5 J extra
Around the floor is 280 J extra
kinetic energy of the wagons
potential energy stored in the spring
both A and B
not enough information
a frictionless pendulum
a mass on a spring in a vacuum