Question

Q1.A boy of 50kg hops with a horizontal velocity of 5m/s on stationary skateboard. The skateboard weights 4 kg . Find the velocity when the board starts rolling.

Answer 1

Answer:

Answer Expert Verified · (50 × 5) + (4 × 0) = v(50 + 4) · 250 + 0 = 54v · 250 = 54v · v = 250/54 · v = 4.62 m/s.

Answer 2

Explanation:

Answer:

The skateboard starts rolling at the speed of 4.62 m/s.

Step-by-step explanation:

Mass of the boy = 50 kg

Intial velocity of the boy = 5 m/s

Weight of the skateboard = 4 kg

Intial velocity of skateboard (the skateboard is stationery) = 0 m/s

According to Law of conservation of momentum:

$\boxed{\sf{m_a u_a +m_b u_b = m_a v_a + m_b v_b}} </p><p></p><p></p><p>$

$\longrightarrow⟶ (50 × 5) + (4 × 0) = v(50 + 4)$

$\longrightarrow⟶ 250 + 0 = 54v$

$\longrightarrow⟶ 250 = 54v$

$\longrightarrow⟶ v = 250/54$

$\longrightarrow⟶ v = 4.62 m/s$

Therefore, the skateboard starts rolling at the speed of 4.62 m/s.