A hoop has mass and radius of 4 kg and 0.37 m, respectively. The hoop start from rest and has a constant angular acceleration with respect to a rotational axis that is perpendicular to the plane of the hoop at its center. The hoop turns through an angle of 16 rad in 6.3 s. Find the net external torque that acts on the hoop.

Acave rescue team lifts an injured spelunker directly upward and out of a sinkhole by means of a motor-driven cable. the lift is performed in three stages, each requiring a vertical distance of 11.0 m: (a) the initially stationary spelunker is accelerated to a speed of 4.80 m/s; (b) he is then lifted at the constant speed of 4.80 m/s; (c) finally he is decelerated to zero speed. how much work is done on the 78.0 kg rescue by the force lifting him during each stage

If a spring has a k value of 100 newtons per meter and it is stretched 0.50 meters, what is the restoring force of the spring?

In the first law of thermodynamics, triangle e=q-w, what does q stand for