A 2 kg body is projected vertically upward with speed 20 m/s. During upward motion a constant resistive force of 4 N acts downward. Take g = 10 m/s². If maximum height is N/3 m, find N.
Physics · Work , Power and Energy · kinetic energy and work energy theorem
JEE Mains NEET JEE Advanced

Question

A 2 kg body is projected vertically upward with speed 20 m/s. During upward motion a constant resistive force of 4 N acts downward. Take g = 10 m/s². If maximum height is N/3 m, find N.

G1 Physics · Accepted Answer

Initial kinetic energy = ½(2)(20²) = 400 J. Total opposing force = mg + 4 = 24 N. At the highest point K = 0, so 400 = 24h ⇒ h = 50/3 m. Hence N = 50.