A 2.0 kg body falls in free fall from rest from a point 5.0 m above the ground. Consider g = 10 m/s². In relation to the body's mechanical energy, we can state that:
I. increases during the entire fall of the body, as the kinetic and potential energies increase;
II. is equal to the sum of the kinetic and gravitational potential energies at any point on the trajectory;
III. at the beginning of the fall is worth 100 J.
Check the correct alternative.

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

Aperson gives a shopping cart an initial push along a horizontal floor to get it moving, and then lets go. the cart travels forward along the floor, gradually slowing as it moves. consider the horizontal force(s) on the cart while it is moving forward and slowing. which of the following statements is correct? (a) both a forward and a backward force are acting on the cart, but the forward force is larger. (b) only a forward force is acting which diminishes with time. (c) both a forward and a backward force are acting on the cart, but the backward force is larger. (d) only a backward force is acting, no forward force.

What causes the development of most clouds and precipitation in the atmosphere?