HELP ASAPPP An object of mass m is moving along a frictionless track with known speed vo to the right. It collides with and sticks to an object of mass 4m moving with known speed v2 to the right. Considering the law of conservation and the law of conservation of momentum and conservation of mechanical energy, must be applied to determine the final speed of the carts, and why?
a
Both conservation of mechanical energy and conservation of momentum, because neither cart changes direction.
b
Only conservation of momentum, because the momentum lost by one cart is gained by the other and there is only one unknown quantity.
c
Either conservation of momentum or conservation of mechanical energy, because only one equation is required to solve for the one unknown variable.
d
Both conservation of mechanical energy and conservation of momentum, because both principles apply in any collision.