Question

A 45.0-kg girl is standing on a 147-kg plank. The plank, originally at rest, is free to slide on a frozen lake, which is a flat, frictionless surface. The girl begins to walk along the plank at a constant velocity of 1.53 m/s to the right relative to the plank. (Let the direction the girl is moving in be positive. Indicate the direction with the sign of your answer.)

Answer 1

Answer:

$v_1 = 1.17 m/s$

Explanation:

given,

mass of the girl (m₁)= 45 kg

mass of the plank(m₂) = 147 kg

constant velocity of girl relative to plank  = 1.53 m/s

velocity relative to ice berg(v₁) = ?

conservation of momentum

momentum of system = 0

$m_1v_1 = m_2v_2$

$45 \times v_1 = 147 \times (1.53 - v_1)$

$45v_1 = 224.91 - 147 v_1$

$192 v_1 = 224.91$

$v_1 = \dfrac{224.91}{192}$

$v_1 = 1.17 m/s$

hence, the velocity relative to ice berg is 1.17 m/s