A 15kW motor hoists an 800. kg bucket of concrete to a floor 90.0 m above ground in a building under construction. If no energy is lost, how much time is needed to do this?I need to show all work.
A watt is 1 N*m/s. So 15 kW is 15,000 N*m/s. The weight of the bucket of concrete is (800 kg)*(9.81 m/s^2) = 7848 N. The speed of the hoist is (15,000 N*m/s)/(7848 N) = 1.911 m/s. So the time it takes to travel 90.0 m is (90.0 m)/(1.911 m/s) = 47.1 seconds.
