A2.5-kg rock is dropped off a 32-m cliff and hits a spring, compressing it 57 cm. what is the spring constant? round your answer to two significant figures.

Amoving electron has kinetic energy k1. after a net amount of work w has been done on it, the electron is moving one-quarter as fast in the opposite direction. (a) find w in terms of k1. (b) does your answer depend on the final direction of the electron's motion?

The sun’s mass is 2.0×10^ 30 kg, its radius is 7.0×10 5 km, and it has a rotational period of approximately 28 days. if the sun should collapse into a white dwarf of radius 3.5×10 3 km, what would its period be if no mass were ejected and a sphere of uniform density can model the sun both before and after?

The water flowing over niagara falls drops a distance of 50 m. if all the gravitational potential energy is converted to thermal energy, by what temperature does the water rise? the specific heat of water is 4186 j/kg ∙ k. a)0.42 c° b)0.37 c° c)0.12 c° d)0.10 c°