Question

A skydiver, who weighs \(650 \mathrm{N},\) is falling at a constant speed with his parachute open. Consider the apparatus that connects the parachute to the skydiver to be part of the parachute. The parachute pulls upward with a force of \(620 \mathrm{N} .\) (a) What is the force of the air resistance acting on the skydiver? (b) Identify the forces and the interaction partners of each force exerted on the skydiver. (c) Identify the forces and interaction partners of each force exerted on the parachute.

Short answer

Answer: The force of air resistance acting on the skydiver is 30 N. The interaction forces between the skydiver and the parachute are the parachute force (620 N) and the air resistance force (30 N). The interaction partners for the skydiver are the Earth (for weight), the parachute (for parachute force), and the air (for air resistance force). The interaction partners for the parachute are the skydiver (for parachute force) and the air (for combined air resistance force).

Step-by-step solution

Determine the Force of Air Resistance on the Skydiver

As the skydiver is falling at a constant speed, the net force acting on him must be equal to zero. We can use this fact to determine the force of air resistance acting on the skydiver. The skydiver's weight is balanced by the sum of the upward parachute force and the air resistance force. So, let's write the equation of motion: $$ \text{Weight} - \text{Parachute Force} - \text{Air Resistance Force} = 0 $$ Now, plug in the given values and solve for the air resistance force: $$ 650 \,\text{N} - 620 \,\text{N} - F_{\text{air}} = 0 \\ F_{\text{air}} = 650 \,\text{N} - 620 \,\text{N} \\ F_{\text{air}} = 30 \,\text{N} $$ The force of air resistance acting on the skydiver is \(30 \,\text{N}\).

Identify the Forces and Interaction Partners for the Skydiver

There are three forces acting on the skydiver: 1. Weight (\(650 \,\text{N}\)) acting downward, this force is due to the Earth's gravity and its interaction partner is the Earth. 2. Parachute force (\(620 \,\text{N}\)) acting upward, this force is due to the tension in the parachute apparatus, and its interaction partner is the parachute. 3. Air resistance force (\(30 \,\text{N}\)) acting upward, this force is due to the interaction between the skydiver and the air molecules, and its interaction partner is the air.

Identify the Forces and Interaction Partners for the Parachute

There are two main forces acting on the parachute: 1. Parachute force (\(620 \,\text{N}\)) acting downward, this force is due to the tension in the parachute apparatus, and its interaction partner is the skydiver. 2. Combined air resistance force acting upward, this force is due to the interaction between the parachute, skydiver, and the air molecules, and its interaction partner is the air. Since the skydiver is falling at a constant speed, this combined force should balance the parachute force, i.e., \(620 \,\text{N}\). Keep in mind that the question only asked about the air resistance force on the skydiver, not the parachute, which is why we didn't calculate the air resistance force for the parachute separately.