The figure shows the speed of a person's body as he does a chin-up. assume the motion is vertical and the mass of the person's body is 64.0 kg. determine the force exerted by the chin-up bar on his body at t = 0s; t = 0.5s; t = 1.1s; and t = 1.6s

Frost wedging occurs when water seeps into a crack in a rock, freezes, and causes the crack in the rock to widen. t or f

The us government wants to allocate billions of dollars in the next 10 years to assure our future energy security. the funds will be spread among a variety of possible energy resources. where do you think the government should put the greatest support: solar energy, wind energy, clean coal, oil exploration, gas exploration, or a combination of sources? are there other efforts that should be explored? support your position with cited information for both questions.

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