Chris is in the process of moving to a new house, and he needs to carry out a lot of boxes from the second floor to his pickup truck. The mass of each box is 53 kg. Instead of carrying boxes out one by one, he has set up a smooth, frictionless slope from the second floor to the first floor so that he can slide down boxes one by one. When a box slides down to the first floor, it continues sliding by a distance of 7.8 m toward the entrance of the house, where the pickup truck is parked. There is a small, frictionless ramp connecting to the bed of the pickup truck so the box can be loaded to the truck effortlessly.
See attached image

The first floor is carpeted, and there is a frictional force of magnitude 140 N on the box as it slides on the carpet. The height difference between the first and second floor is 3.2 m, and the height difference between the first floor and the bed of the pickup truck is 0.90 m.

A box is initially at rest on the second floor, and Chris pushes the box toward the slope so that the speed of the box is 2.1 m/s right before it starts sliding down the slope. The second floor is smooth, and the frictional force between the second floor and the box is negligible.

Use g = 10 m/s2 for the acceleration due to gravity.



(1)
What is the work done by Chris on the box when the speed of the box reaches 2.1 m/s?

(2)
What is the speed of the box when it reaches the bottom of the slope (Point B in the diagram)?

(3)
To what speed does the box slow down when it reaches to the bottom of the ramp to the pickup truck?

(4)
What is the speed of the box when it reaches the bed of the pickup truck?

(5)
If instead Chris just pushes the box off the slope from rest (i.e., initial speed is 0 m/s), does the box make it to the bed of the truck? Assume that the magnitude of the frictional force is still 140 N. Show your calculation to support your answer.