An elevator is rising at constant speed. Select the correct statements (s) :

Options

A. the upwards cable force is constant
B. the kinetic energy of the elecator is constant
C. the gravitational potential energy of the Earth-elevator system is constant
D. the mechanical energy of the Earth-elevator system is constant

Answer

AB

Explanation

(A) is correct because T=mg
(B) is correct because `1/2 mv^(2)`=const.
(C) is wrong because distance between earth and elevator is changing.
(D) is wrong because u of the system is changing.