A 1200-Kg Ore Cart Is Rolling at 10 $858 \mathrm {~kg}$

Multiple Choice

A 1200-kg ore cart is rolling at 10.8 m/s across a flat friction-free surface.A crane suddenly drops $858 \mathrm {~kg}$ of ore vertically into the cart.How fast does the cart move just after being loaded with the ore?

A) 6.30 m/s
B) 3.80 m/s
C) 4.20 m/s
D) 5.70 m/s