Abox of mass 45 kg slides down a ramp onto a flat surface. the box slides a distance of 4.9 m across the flat surface and then stops. the coefficient of friction between the flat surface and the box is 0.39. what was the speed of the box at the base of the ramp?

6.1 m/s

0.77 m/s

3.0 m/s

19 m/s

On a frictionless air track, a blue glider with mass 0.200 kg is moving to the right with a speed of 8.00 m/s. it strikes a red glider that has mass 0.600 kg and that is initially at rest. after the collision, the blue glider is moving to the left with a speed of 3.00 m/s.(a) what are the magnitude and direction of the velocity of the red glider after the collision? (b) is this collision elastic?