Question

felix baumgartner made history by skydiving from earths stratosphere. the free body diagram below shows four different time points in his fall, from diagram a - just after leaving his capsule to d - after he has been in free fall for some time. students were asked to rank the images in terms of the acceleration experienced by the skydiver felix baumgartner at each point from greatest to least. what is the correct order?

b. c. d = a: the skydiver must be falling for a few seconds in order to accelerate (b). then the air resistance increases which would decrease the net force on the skydiver and cause him to slow down (c). the skydivers acceleration at a and d would be the same because he would not experience an acceleration at first because he hasnt been falling for long (a) and in d he has reached terminal velocity.
a a=b=c=d: the acceleration due to gravity is always 10 m/s² so the acceleration is identical for each scenario.
d. c. b. a: the vector arrows show the magnitude of the forces acting on a body. at point d, the vector arrows are the longest so when they are added the net force is very large resulting in a large acceleration. from points c to b, the vector representing f_air gets smaller so the net force will be decreasing. there is only one vector arrow present at point a so the net force there would be the least.
a. b. c. d: the skydiver experiences the least resistance immediately after leaving the helicopter (a), therefore his net force is greatest and his acceleration will be greatest. as he falls, air resistance on him increases which would decrease the net force (b to c). at point d, the skydiver

Explanation:

Step1: Apply Newton's second law

Newton's second law is \(F_{net}=ma\), where \(F_{net}\) is the net force, \(m\) is the mass, and \(a\) is the acceleration. The mass of the skydiver \(m\) is constant. So, the acceleration \(a\) is directly proportional to the net force \(F_{net}\). The net force \(F_{net}=F_{g}-F_{air}\) (taking down - ward as positive, \(F_{g}\) is the gravitational force and \(F_{air}\) is the air - resistance force).

Step2: Calculate the net force for each diagram

• For Diagram A: \(F_{netA}=F_{g}-0 = 900N\) (since there is no air - resistance just after leaving the capsule, \(F_{airA} = 0\))
• For Diagram B: \(F_{netB}=F_{g}-F_{airB}=900 - 300=600N\)
• For Diagram C: \(F_{netC}=F_{g}-F_{airC}=900 - 600 = 300N\)
• For Diagram D: \(F_{netD}=F_{g}-F_{airD}=900 - 900=0N\)

Step3: Rank the accelerations

Since \(a=\frac{F_{net}}{m}\) and \(m\) is constant. The order of net forces from greatest to least is \(F_{netA}>F_{netB}>F_{netC}>F_{netD}\). So the order of accelerations (because \(a\propto F_{net}\)) is \(A > B > C > D\)

Answer:

D. A, B, C, D: The skydiver experiences the least resistance immediately after leaving the helicopter (A), therefore his net force is greatest and his acceleration will be greatest. As he falls, air resistance on him increases which would decrease the net force (B to C). At point D, the skydiver