Question

A 45.0 - kg girl is standing on a 150. - 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 1.50 m/s to the right relative to the plank. What is her velocity relative to the surface of the ice?

Answer 1

Answer:

The velocity relative to the surface of the ice is 6.5 m/s.

Explanation:

Given that,

Mass of girl m= 45.0 kg

Mass of plank M= 150 kg

Velocity = 1.50 m/s

We need to calculate the velocity relative to the surface of the ice

Using conservation of momentum

$mv_{1}+Mv_{2}=(m+M)v$

Here, $v_{2}=0$ because plank at rest

$v_{1}=\dfrac{m+M}{m}\times v$

Put the value into the formula

$v_{1}=\dfrac{45+150}{45}\times1.50$

$v_{1}=6.5\ m/s$

Hence, The velocity relative to the surface of the ice is 6.5 m/s.