Den pushes a desk 400 cm across the floor. He exerts a force of 10 N for 8 s to move the desk.

What is his power output? (Power: P = W/t)

1.25 W
5 W
40 W
500 W

Alunar lander is making its descent to moon base i. the lander descends slowly under the retro-thrust of its descent engine. the engine is cut off when the lander is h = 5.5 m above the surface and has a downward speed of 0.8 m/s. with the engine off, the lander is in free fall. what is the speed of the lander just before it touches the surface? the acceleration due to gravity on the moon is 1.6 m/s2.