A3.78-kn piano is lifted by three workers at a constant speed to an apartment 29.2 m above the street using a pulley system fastened to the roof of the building. each worker is able to deliver 144 w of power, and the pulley system is 75.0% efficient (so that 25.0% of the mechanical energy is lost due to friction in the pulley). neglecting the mass of the pulley, find the time required to lift the piano from the street to the apartment.

Which sentences describe disadvantages of burning fossil fuels instead of using hydrogen fuel cells? burning fossil fuels contributes to climate change. burning fossil fuels takes place inside expensive fuel cells. fossil fuels aren't widely available, but pure hydrogen is. fossil fuels are nonrenewable.

You throw a baseball directly upward at time =0 at an initial speed of 14.9 m/s. what is the maximum height the ball reaches above where it leaves your hand? ignore air resistance and take =9.80 m/s2.

Hydroelectricity provides about 7 percent of the electricity generated in the united states. (a) explain how a hydroelectric power plant converts energy stored in water into electricity. (b) identify two factors that determine the amount of electricity that can be generated by an individual hydroelectricity power plant. (c) describe the two main types of land-based hydroelectric power plants. (d) describe two economic advantages and two environmental disadvantages of hydroelectricity.