Question

A Block Of Mass 1 Kg Is Horizontally Thrown With A Velocity Of 10 Metre Per Second On A Stationary Long Plank Of Mass 2Kg Whose Surface Has Mu Is Equal To 0.5 Plank Race On Frictionless Surface Find The Time When Block Comes To Rest With Respect To Plank

Answer 1

Answer:

4/3 secs

Explanation:

Given A Block Of Mass 1 Kg Is Horizontally Thrown With A Velocity Of 10 Metre Per Second On A Stationary Long Plank Of Mass 2 Kg Whose Surface Has Mu Is Equal To 0.5 Plank Race On Friction less Surface Find The Time When Block Comes To Rest With Respect To Plank

Let the velocity of the system when block comes in rest with respect to plank be V. By conservation of momentum we get

1 x 10 = (2 +  1) V

Now V = 10/3

So force on the block is μ x m x g = 0.5 x 1 x 10 = 5 N

Now deceleration of block is a = 5/1 = 5 m / s^2

Let time to change velocity of block from 10 to 10/3 is t, then

10 – 10/3 = at = 5 x t

5t = 20/3

t = 4/3 secs

The Time When Block Comes To Rest With Respect To Plank is 4/3 secs