See if you get the answer with this formulae.
Answer:
Since the momentum of the body remains constant ( conserved) the trolley slows down (its velocity reduces) since its mass increases.
Answer:
Energy lost due to friction is 22 J
Explanation:
Mass of the ball m = 4 kg
Initially velocity of ball v = 6 m/sec
So kinetic energy of the ball 

Now due to friction velocity decreases to 5 m/sec
Kinetic energy become

Therefore energy lost due to friction = 72 -50 = 22 J
-- The source of most of the energy that radiates from the sun is nuclear energy.
-- Most of the energy that radiates from the sun is electromagnetic energy.
-- Heat energy is part of the electromagnetic energy that radiates from the sun.
Other parts include radio, microwave, visible light, ultraviolet, and X-ray energy.
They interact with one another with their facial expressions and body movements all the time