Question about terminal speed using drag

In summary, the terminal speed of a 75 kg man jumping out of a plane feet first can be calculated using the equation v terminal = sq rt (4mg/p* area), where the cross-sectional area of the man should be used as 1.8 m * .40m = .72. The correct area to use is .20 * .40, which results in a terminal speed of 170 m/s.
  • #1
sona1177
173
1
What is the terminal speed of a 75 kg man that jumps out of a plane feet first? The man can be thought of as a rectangular box with dimensions 20 cm * 40 cm * 1.8 m

I tried equation v terminal = sq rt (4mg/p* area). P=1.22
I used . 72 as Area. That's wrong. Help please!

I calculated eq using .72 but that is wrong. Help!
 
Physics news on Phys.org
  • #2
What area should be used in the equation for terminal velocity?

ehild
 
  • #3
See my book says to use the cross sectional area. The answer is supposed to be 170 m/s but I am very frustrated because I can't see how they got that. His cross sectional area is 1.8 m * .40m =.72 but it's wrong if you use this.
 
  • #4
Oh i see what you are saying, since he jumps out feet first, that means the area is .20 * .40, this side meets air resistance. If you use this in the eq the value is 170 m/s and that's the answer. Is my reasoning correct?
 
  • #5
sona1177 said:
Oh i see what you are saying, since he jumps out feet first, that means the area is .20 * .40, this side meets air resistance. If you use this in the eq the value is 170 m/s and that's the answer. Is my reasoning correct?

Yes, that is the clue, feet first! Good job!

ehild
 
  • #6
Thanks for all your help!
 

FAQ: Question about terminal speed using drag

1. What is terminal speed?

Terminal speed, also known as terminal velocity, is the maximum velocity that an object reaches when falling through a fluid, such as air or water. It is the point at which the forces of gravity and air resistance (drag) are balanced, resulting in a constant velocity.

2. How is terminal speed calculated?

The formula for calculating terminal speed is given by Vt = √(2mg/ρACd), where Vt is the terminal speed, m is the mass of the object, g is the acceleration due to gravity, ρ is the density of the fluid, A is the cross-sectional area of the object, and Cd is the drag coefficient.

3. What factors affect terminal speed?

The factors that affect terminal speed include the mass and shape of the object, the density of the fluid, and the presence of any external forces, such as wind or air currents. Objects with a larger cross-sectional area or a lower drag coefficient will have a lower terminal speed, while those with a smaller cross-sectional area or a higher drag coefficient will have a higher terminal speed.

4. How does drag force affect terminal speed?

Drag force is the force that opposes the motion of an object through a fluid, and it increases as the speed of the object increases. As an object falls through a fluid, the drag force will increase until it becomes equal to the force of gravity, resulting in a constant terminal speed.

5. Can terminal speed be exceeded?

Terminal speed is the maximum speed that an object can reach while falling through a fluid, so it cannot be exceeded. However, if the object continues to accelerate due to an external force, such as gravity, it may eventually reach a new, higher terminal speed.

Similar threads

How do I find the terminal speed of a body in water?
Replies
13
Views
4K
Terminal velocity of a skier using a Momentum Balance
Replies
1
Views
1K
Drag, terminal velocity, and force.
Replies
9
Views
4K
What is the drag force on a car traveling at different speeds?
Replies
6
Views
12K
Linear drag in a liquid and terminal velocity
Replies
1
Views
5K
Calculating the Speed of a Cricket Ball with Drag Force: Homework Problem
Replies
2
Views
2K
Calculating Skydiver Terminal Speed: A Drag Problem Solved
Replies
2
Views
24K
Variable acceleration and terminal velocity
Replies
11
Views
3K
Ski Jump Ramp: Calculating Gravitational Work, Total Speed, and Air Drag
Replies
7
Views
2K
Compute the terminal speed of a car as it coasts down the incline
Replies
5
Views
5K

Hot Threads

Recent Insights

Back
Top