Question

9 The ball is allowed once more to slide down the slide-slot, starting at rest from point R. However, this time
the slide-slot is unconstrained horizontally so that it is free to slide on the table. While sliding, the ball is
always in contact with the slide-slot. The mass of the slide-slot is 500 g.
gravitational acceleration (g) of a free-falling object is 10 m s-2.
As the ball slides down the curved surface, from point R to point T, the total mechanical energy (sum of
kinetic and gravitational potential energies) of the ball
A
decreases only.
B
increases only.
C
remains constant.
D

Answer 1

Since there was no friction or rough surface contact, it suggests that there was no non conservative forces which consuming the energy during the motion and also conservation of energy always valid

Total energy at point R(Sum total of kinetic and potential energies ) = Total energy at point T( Sum total of kinetic and potential energies)

Note : there was no need to consider any mathematics to prove it