Question

A child is sitting on a swing. Its minimum and maximum heights from the ground 0.75m and 2m respectively, its maximum speed will be _____________

(a) 10 m/s

(b) 5 m/s

(c) 8 m/s

(d) 15 m/s

The question was asked in homework.

My doubt stems from Relation between Torque and Momentum topic in section System of Particles and Rotational Motion of Engineering Physics I

Answer 1

Right answer is (b) 5 m/s

Explanation: Maximum kinetic energy = Drop in potential energy

1/2 mv^2=mg(h2-h1)

v=√(2g(h2-h1))=√(2×10(2-0.75))=5m/s.