Power can be described as

Leah is helping to build a water habitat in a neighborhood park. The habitat includes an upper pond connected to a lower pond, 3.2 m below, by a trickling stream with several small cascades. At a home-building store, she finds a 45-W pump that has a maximum circulation rate of 1900 L of water per hour. Can the pump develop enough power to raise the water from the lower to the upper pond? (The mass density of water, ρ, is 1.00 kg/L)

An electric motor lifts an elevator at a constant speed of 54.0 km/h. The engine must exert a force of 9.00 kN in order to balance the weight of the elevator and the friction in the elevator cable. What power does the motor produce in kW?

Ali uses a pulley system to raise a 30.0-kg carton a vertical distance of 15.3 m. He exerts a force of 211 N and pulls the rope 28.0 m.

What is the efficiency of the system? (hint, find MA first)

Rohit lifts a 89-kg crate by exerting a force of 120 N on a lever, through a distance of 1.6 m. The efficiency of the lever is 92 percent. How far is the crate lifted?

A player pushes a 250-g hockey puck over frictionless ice with a constant force, causing it to accelerate at 24 m/s² over a distance of 50.0 cm.

Find the work done by the hockey player on the puck.

A wagon is pulled by a force of 38.0 N exerted on the handle at an angle of 42.0° with the horizontal. If the wagon is pulled for 157 m, how much work is done on the wagon?

A lawn roller is pushed across a lawn by a force of 115 N along the direction of the handle, which is 22.5° above the horizontal. If 64.6 W of power is developed for 90.0 s, what distance is the roller pushed?

Which requires more work—carrying a 420-N backpack up a 200-m-high hill or carrying a 210-N backpack up a 400-m-high hill?

Sally does 11.4 kJ of work dragging a wooden crate 25.0 m across a floor at a constant speed. The rope she uses to pull the crate makes an angle of 48.0° with the horizontal. What force does the rope exert on the crate?

A worker uses a pulley to raise a 24.0-kg carton 16.5 m, as shown in Figure 15. A force of 129 N is exerted, and the rope is pulled 33.0 m.

What is the efficiency of the pulley?

You exert a force of 225 N on a lever to raise a 1.25×10³ N rock a distance of 13 cm. If the efficiency of the lever is 88.7 percent, how far did you move your end of the lever?

An elevator lifts a total mass of 1.1×10³ kg a distance of 40.0 m in 12.5 s. How much power does the elevator deliver?

A forklift raises a box 1.2 m and does 7.0 kJ of work on it. What is the mass of the box?