Air drag and acceleration (not gravity)

In summary, to find the air drag acting on the rocket, you will need to use the formula Fd = 1/2 * ρ * v2 * Cd * A and calculate the velocity of the rocket at different points in time using the equation v = u + at.
  • #1
Unstoppable13
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In physics class we made a rocket and test fired it. Now we are given the thrust and we found out the max height of the rocket and the time of flight.

Max Height = 76m
Time of thrust/ upward acceleration = .8s
Time of flight with only gravity acting until velocity is 0 . = 4.96s (not including downward fall)
Mass of rocket = 0.08 kg
Fg= 0.8N
g= 9.8m/s^2

Now we are supposed to find the air drag acting on the object. But I have no clue on how to do that because all the formulas relate to velocity, which is not really a given because the rocket is accelerating upwards. So is there a formula that I can use to solve this?
 
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  • #2
Yes, there is a formula that you can use to solve this. The formula for air drag is: Fd = 1/2 * ρ * v2 * Cd * A where ρ is the density of air, v is the velocity of the rocket, Cd is the drag coefficient, and A is the area of the rocket. To calculate the air drag, you will need to calculate the velocity of the rocket at different points in time. You can do this by using the equation: v = u + at where u is the initial velocity (which is 0 in this case), a is the acceleration due to thrust (Fg/m where m is the mass of the rocket) and t is the time. Once you have the velocity, you can then calculate the air drag using the formula above.
 
  • #3


To calculate the air drag on an object, you will need to use the formula Fd = 1/2 * ρ * v^2 * Cd * A, where Fd is the air drag force, ρ is the density of air, v is the velocity of the object, Cd is the drag coefficient, and A is the cross-sectional area of the object. In this case, since the rocket is accelerating upwards, you will need to use the average velocity during its flight, which can be calculated by dividing the distance traveled (76m) by the time of flight (4.96s). Once you have the average velocity, you can plug it into the formula along with the other given values to calculate the air drag force acting on the rocket. Keep in mind that the drag coefficient and cross-sectional area may vary depending on the shape and size of the rocket, so you may need to do some research or experimentation to find those values.
 

FAQ: Air drag and acceleration (not gravity)

1. What is air drag?

Air drag, also known as air resistance, is a force that opposes the motion of an object through the air. It is caused by the collision of air molecules with the surface of the object.

2. How does air drag affect the acceleration of an object?

Air drag can decrease the acceleration of an object by exerting a force in the opposite direction of the object's motion. This is because the force of air drag acts against the force of the object's motion, resulting in a net force that is less than the force of gravity.

3. Does air drag affect all objects equally?

No, air drag affects objects differently depending on their shape, size, and speed. Objects with larger surface areas or higher speeds will experience more air drag than objects with smaller surface areas or lower speeds.

4. How can air drag be reduced?

Air drag can be reduced by changing the shape of an object to make it more streamlined, reducing its surface area, or decreasing its speed. Additionally, using materials that are more aerodynamic can also help to reduce air drag.

5. Is air drag always a hindrance to an object's motion?

No, air drag can also be used to an advantage in certain situations. For example, it can be used to control the descent of a parachute or to help airplanes generate lift. In these cases, air drag is not a hindrance but rather a useful force.

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