Abullet of 0 01kg is fired horizontally into a 4kg wooden blockat rest on a horizontal surface, the coefficient of - Physics -

Question

Abullet of 0 01kg is fired horizontally into a 4kg wooden
blockat rest on a horizontal surface, the coefficient of kinetic
frictio between the block and surface being 0 25 The bullet remains
embedded in the block and the whole system moves20m before coming
to rest With what velocity did the bullet strike the block?

Hansraj Rai · Accepted Answer

Let v be the velocity of the bullet and V be the velocity of combined mass.

Final velocity of the combined mass is zero.

Let m and M be the mass of the bullet and the wooden box respectively.

Combined mass is , M' = m + M

$F = μ R = μ (M' g) M' a = μ (M' g) a = μ g$

As force is acting in backward direction,

$a = - μ g$

Using the equation,

${(0)}^{2} - V^{2} = 2 a s - V^{2} = - 2 μ g s V^{2} = 2 μ g s V = 9.9 m / s$

According to the conservation of the momentum,

$m v + M \times 0 = (m + M) \times V ..... (i)$

On substituting the value in equation (i), you will get the answer.