Look at the vector i plotted below.
What is the correct way to describe this vector?

20. threshold braking in the vehicle's braking system occurs when a. the brake pedal is pushed, heel on floorboard, with full foot pressure. b. the brakes are exerting full braking power, without traction loss. c. the driver begins pushing down the brake pedal, with moderate slowdown. d. the brakes just begin to take hold with a gradual slowdown.

The graph describes the motion of an object. the object moves with from a to b. it from b to c. it moves with from c to d.

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.