11. An 83 kg parachutist jumps out of an airplane, and experiences 120 N of air resistance.a) Draw a free body diagram. b) Determine their acceleration at the time. c) How manyseconds will it take to reach a terminal speed of about 200 km/h? (Answer: a=8.4 m/s2,6.6 s)

a) A free body diagram would show two forces acting on the parachutist: the force of gravity acting downwards and the force of air resistance acting upwards.

b) To determine the acceleration, we first need to find the net force acting on the parachutist. The force of gravity (weight) can be calculated using the formula F = m*g, where m is the mass and g is the acceleration due to gravity (9.8 m/s^2). So, the weight of the parachutist is 83 kg * 9.8 m/s^2 = 813.4 N. The net force is then the weight minus the air resistance: 813.4 N - 120 N = 693.4 N.

The acceleration can be found using Newton's second law, F = m*a, where F is the net force and m is the mass. Solving for a gives a = F/m = 693.4 N / 83 kg = 8.36 m/s^2, which rounds to 8.4 m/s^2.

c) Terminal speed is the constant speed that a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration. This occurs when the force due to air resistance equals the weight of the object.

To find the time it takes to reach this speed, we first need to convert the terminal speed from km/h to m/s: 200 km/h * (1000 m/1 km) * (1 h/3600 s) = 55.56 m/s.

Then, we can use the formula for the time taken to reach a certain velocity under constant acceleration: t = v/a, where v is the terminal velocity and a is the acceleration. So, t = 55.56 m/s / 8.4 m/s^2 = 6.61 s, which rounds to 6.6 s.