How much kinetic energy a spring that streches 4m would be?

Suppose that a comet that was seen in 563 a.d. by chinese astronomers was spotted again in year 1951. assume the time between observations is the period of the comet and take its eccentricity as 0.986. what are (a) the semimajor axis of the comet's orbit and (b) its greatest distance from the sun?

Atrain departs from its station at a constant acceleration of 5 m/s. what is the speed of the train at the end of 20s?

If the ama of the inclined plane below is 2, calculate the ima and efficiency. ima = efficiency =