Question

A 1200-kg ore cart is rolling at 10.8 m/s across a flat friction-free surface. A crane suddenly drops of ore vertically into the cart. How fast does the cart move just after being loaded with the ore?

4.20 m/s
	6.30 m/s
	5.70 m/s
	3.80 m/s

Answer 1

Solution:

Given:

Mass of cart (m₂) = 1200 kg
Initial velocity of cart (v₁) = 10.8 m/s

Mass of ore (m₂) = ** NOT GIVEN **

But if you have the value of Mass of ore (m₂) with you. then use the following method to solve for final velocity:

Let final velocity be: V_f
Here, According to conservation of momentum: m₁ v₁ = (m₁ + m₂) V_f
Therefore: V_f  = { m₁ v₁ }/ (m₁ + m₂)

Plug in the given values in above equation to get final answer:

Answer 2

M1*V1/M1+M2=1200*10.8/(1200+989)=5.921