Which of the following has the greatest power
A) A weight lifts that lifts as 250N weight 2.1mm 2sec
B) A mechanic's lifts that raises a 1.2×10000 N car 2.1m in 12 sec
c ) A car Engine that does 1.2 × 1000J work in 5sec
D) A crane that lifts a 2.5 × 10000 N beam at a speed of 1.2 m/s

Consider an ordinary, helium-filled party balloon with a volume of 2.2 ft3. the lifting force on the balloon due to the outside air is the net resultant of the pressure distribution exerted on the exterior surface of the balloon. using this fact, we can derive archimedes’ principle, namely that the upward force on the balloon is equal to the weight of the air displaced by the balloon. assuming that the balloon is at sea level, where the air density is 0.002377 slug/ft3, calculate the maximum weight that can be lifted by the balloon. note: the molecular weight of air is 28.8 and that of helium is 4.

Which example has gravitational potential energy? a.a horse slowing down from a run b.an apple about to fall from a tree branch c.a bicycle being pedaled down a horizontal path d.beaker sitting on the floor

Astudent pushes a 60-n block across the floor for a distance of 10 m. how much work was done to move the block