JEE Main20198 Apr 2019Evening ShiftPhysicsRotational MotionActual
A rectangular solid box of length 0.3 m is held horizontally, with one of its sides on the edge of a platform of height 5 m . When released, it slips off the table in a very short time τ = 0.01 s , remaining essentially horizontal. The angle by which it would rotate when it hits the ground will be (in radians) close to:
Options
- A0.5
- B0.3
- C0.02
- D0.28
Correct answer
A. 0.5
Step-by-step solution
Angular impulse = change in angular momentum τ Δ t = Δ L m g l 2 × 0.01 = m l 2 3 ω ω = 3 g × 0.01 2 l = 3 × 10 × 0.01 2 × 0.3 = 0.5 r a d / s e c Time taken by rod to hit the ground = 2 h g = 2 × 5 10 = 1 s Angle rotated by rod = ω t = 0.5 × 1 = 0.5 r a d