JEE Main2015PhysicsWork, Power and EnergyActual
A block of mass m = 10 kg rests on a horizontal table. The coefficient of friction between the block and the table is 0 . 05 . When hit by a bullet of mass 50 g moving with speed v , that gets embedded in it, the block moves and comes to stop after moving a distance of 2 m on the table. If a freely falling object were to acquire speed v 10 after being dropped from height H , then neglecting energy losses and taking g
Options
- A0 . 2   km .
- B0 . 5   km .
- C0 . 4   km .
- DNone of these.
Correct answer
D. None of these.
Step-by-step solution
By the conservation of linear momentum, m 1 v = m + m 1 v 1 ⇒ v 1 = m 1 v m + m 1   . . . ( 1 ) After collision by work energy theorem, we have W friction = ∆ k ⇒ - μ m + m 1 g x = - 1 2   m + m 1 v 1 2 ⇒ μ g x = 1 2 v 1 2 ⇒ 0.05 × 10 × 2 = 1 2 m 1   v m + m 1 2 ⇒ 5 100 × 10 × 4 = 50 1000 2 × v 2 10 +   50 1000 2 ⇒ 2 = 1 400 v 2 × 400 201 2 v 2 = 201 2   2 v = 2 × 201 For a freely falling body, v ' =