# Distance to reach terminal velocity experiment

• tomtristan
In summary: I would say that if the sphere is dropped from a height of 2 metres, it will be within 0.5 metres of terminal velocity.
tomtristan
I am planning an experiment for my coursework in which i am dropping spheres of different mass and calculating their drag. They will be of different sizes, but are made of plastercine so are relatively light. I would guess the heaviest would weigh no more than 20 grams.

Does anybody know roughly how far the heaviest of these balls would have to be dropped before it reaches terminal velocity? Because if possible i want to do my experiment in the classroom without having to drop something out the window and take my equipment outside.

Any estimates would be much appreciated.

Welcome to PF tom,

It is possible to calculate the distance taken for your spheres to reach terminal velocity , but I can tell you without calculation, that it's going to take a distance greater than the height of a room.

Thankyou. I think it might be best if i did an initial experiment from a large height so it has time to reach terminal velocity, and working out the drag coefficient for different spheres. Would the drag coefficients stay constant, so i can use them to work out the drag at velocitys below terminal velocity?

well, but having in consideration that the esphers are not perfect and a lot more factors, i guess that's not necessary...i made that experience and only had to use about 0.5m to get satisfiyng results...^_^

ahh, don't use only 1 esphere of each size...I used 10 equal espheres and the results vary a little, so 1 is a bad aproximation.

tom:
In a standard mathematical modelling of a fall, your balls will NEVER reach terminal velocity, but will, in FINITE time, come arbitrarily close to it.

Thus, you have two options:
1. Specify an acceptable error margin on the "terminal" velocity, and we may oblige you with an answer.

2. Develop a mathematical model of fall with air resistance, CONSISTENT WITH OBSERVATIONS, that DOES predict a finite time for terminal velocity to be reached.

I'm not saying that 2. is impossible, but I will strongly advise you to choose option 1. instead.

arildno said:
tom:
In a standard mathematical modelling of a fall, your balls will NEVER reach terminal velocity, but will, in FINITE time, come arbitrarily close to it.

Thus, you have two options:
1. Specify an acceptable error margin on the "terminal" velocity, and we may oblige you with an answer.

2. Develop a mathematical model of fall with air resistance, CONSISTENT WITH OBSERVATIONS, that DOES predict a finite time for terminal velocity to be reached.

I'm not saying that 2. is impossible, but I will strongly advise you to choose option 1. instead.

If instead i was to ask what the error margin would be if i was going to drop the spheres from 2 metres, would be be able to oblige me with an answer?
My experiment is not going to be hugely accurate anyway, as the density of the spheres won't be even, as they have to contain a magnet, because i am dropping the spheres through a magnetic circuit and using the induced emf to calculate velocity.

tomtristan said:
If instead i was to ask what the error margin would be if i was going to drop the spheres from 2 metres, would be be able to oblige me with an answer?
Sure, then your ACTUAL question woulkd be:
How close will I be to the terminal velocity during a fall of length two meters?

arildno said:
Sure, then your ACTUAL question woulkd be:
How close will I be to the terminal velocity during a fall of length two meters?

Yes, thankyou. Sorry, i hadn't thought about the question properly before i asked, I've really just been trying to see if my idea is feasible to use for my coursework. It would be great if you could answer though.

## 1. What is a distance to reach terminal velocity experiment?

A distance to reach terminal velocity experiment is a scientific investigation that measures the distance an object travels before reaching its maximum velocity, also known as terminal velocity. Terminal velocity is the point at which the object is no longer accelerating due to the force of gravity and reaches a constant speed.

## 2. How is the distance to reach terminal velocity experiment conducted?

The experiment typically involves dropping an object from a certain height and measuring the distance it travels before reaching its terminal velocity. This can be done by using a stopwatch to record the time it takes for the object to fall, and then using the equation d = 1/2 gt^2 to calculate the distance traveled.

## 3. What factors can affect the distance to reach terminal velocity?

The distance to reach terminal velocity can be affected by factors such as the mass and shape of the object, the density and viscosity of the medium it is falling through, and the force of air resistance. These factors can all influence the object's acceleration and therefore its terminal velocity.

## 4. Why is the distance to reach terminal velocity experiment important?

This experiment is important because it helps us understand the concept of terminal velocity and how it is affected by different variables. It can also be applied to real-world situations, such as calculating the distance a skydiver will fall before reaching terminal velocity.

## 5. What are the applications of the distance to reach terminal velocity experiment?

The distance to reach terminal velocity experiment has practical applications in various fields such as physics, engineering, and sports. It can be used to study the motion of objects in free fall, design parachutes or air resistance equipment, and analyze the performance of athletes in sports such as long jump and ski jumping.

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