An elevator is pulled vertically upwards by a cable. The velocity-time graph for the motion is shown above. Find

1. the distance travelled by the elevator,
2. the acceleration during the first stage and the deceleration during the third stage.

The mass of the elevator is 800 kg and there is a box of mass 100 kg on the floor of the elevator.

3. Find the tension in the cable in each of the three stages of the motion.
4. Find the greatest and least values of the magnitude of the force exerted on the box by the floor of the elevator.