JEE Main 2024 · 6 April · evening · Single correct · +4 / −1
A body of weight 200 N is suspended from a tree branch through a chain of mass 10 kg. The branch pulls the chain by a force equal to (if g=10 m / s²) :
- (a) 300 N
- (b) 100 N
- (c) 150 N
- (d) 200 N
Answer and solution
Answer (a) 300 N
Solution
Physics sir · 3 steps
Take the chain and the body together as one system: the branch must hold up all of it.
- Choose the system. Draw one free body diagram for the chain and the body together. The pull of the chain on the body is then an internal force and drops out.
- Forces on it. Downward: the body's weight 200 N and the chain's weight m g = 10 × 10 = 100 N. Upward: only the pull F of the branch on the top of the chain.
F = 200 N + 100 N = 300 N
- So. Everything hangs at rest, so the upward pull balances the total weight. The branch pulls the chain with 300 N, option (a).
The idea to keep. When something hangs at rest from a massive chain or rope, the support carries the load plus the chain's own weight. Only a massless string passes the load on unchanged.
Answer from the NTA final answer key. Solution by PrepWiser.