8. A 78-kg parachutist, in the first few seconds of her jump, accelerates at a rate of 7.4m/s[V]. Calculate the force she experiences due to air resistance.

9. A 100 kg man gets in an elevator on the 10th floor. He stands still on a scale, which is placed on the floor of the elevator, before the doors close, and the scale reads a value equal to his weight (the largest force of gravity on him). The doors close, and the elevator starts moving downward toward the 1st floor. The elevator speeds up until it reaches the 8th floor, at which point the elevator travels at a constant velocity, which it maintains until it reaches the 3rd floor, at which point it starts slowing down at a constant rate and stops by the time it reaches the 1st floor. Rank from greatest to least, the following quantities at following floors: 2nd, 5th, 9th. Explain your answers. (a) His mass (the question is asking for a ranking of the person's mass on the 2nd floor vs. the mass on the 5th floor vs. the mass on the 9th floor.) (b) His weight (c) Magnitude of normal force he exerts on the scale (d) Magnitude of normal force he exerts on the elevator floor.

10. If two objects are dropped in an environment without air resistance, what will occur? Both of the objects will fall with constant velocity O The lighter of the two objects will fall faster than the heavier. O The heavier of the two objects will fall faster than the lighter. O The objects will accelerate downward at the same rate.

3. Let m, = 15.0 kg, m,= 1.00 kg, and m, = 3.00kg. Solve for the acceleration of the system H, = 0 assuming the system moves to the right. "x = 0.20 300