When you take off in a jet aircraft, there is a sensation of being pushed back into the seat. explain why you move backward in the seat—is there really a force backward on you? (the same reasoning explains whiplash injuries, in which the head is apparently thrown

Newton's third law of motion

Explanation:

As per Newton's third law of motion, every action has its equal and opposite reaction.

When a jet aircraft takes off it exerts a force and gains upward acceleration, the same force is applied on your body as it is moving along the jet hence this force tries to push you back into the seat.

For instance, while rowing a boat you try to apply force on water with paddles in backward direction, the same amount of force is reverted by water thus moving the boat in forward direction.

Hence Newton's third law of motion explains the phenomena.

15.3 cos 65 degrees trig

a and b sometimes have a positive value