Calculate Speed & Acceleration for Weights Dropped from 10m

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Discussion Overview

The discussion revolves around calculating the speed and acceleration of weights dropped from a height of 10 meters. Participants explore the effects of mass, gravitational acceleration, and atmospheric conditions on the falling weights, with a focus on both theoretical and practical aspects of the problem.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Dominic inquires about the speed and time it takes for weights to fall from 10 meters, specifically asking for a detailed answer for one weight.
  • Some participants note that the rate of descent can be influenced by atmospheric conditions and the distribution of weight, referencing how parachutes operate.
  • One participant presents the equation x=Vi + 1/2(gt^2) to describe the motion, stating that the mass of the weights does not affect the velocity at which they hit the ground.
  • Another participant mentions that gravitational acceleration is approximately 9.8 m/s², emphasizing that weight does not factor into the calculations of acceleration and velocity, only air resistance does.
  • There is a discussion about the assumption that the weights are solid metal and spherical, suggesting that they would fall at the same rate regardless of mass, barring experimental inaccuracies.
  • Participants engage in a light-hearted exchange about typographical errors in the equations presented, indicating a casual tone in parts of the discussion.

Areas of Agreement / Disagreement

Participants generally agree that the mass of the weights does not affect the speed of descent in a vacuum, but there is some contention regarding the effects of atmospheric conditions and the accuracy of measurements. No consensus is reached on the exact parameters influencing the fall.

Contextual Notes

Some assumptions about the conditions of the drop (e.g., atmospheric drag, shape of the weights) remain unexamined, and there are unresolved details regarding the application of the equations presented.

Dragonetti
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Hi,
I am new to physics and the physics forum, I have a question.

I have a series of weights, 2kgs, 4kgs, 6kgs etc, held 10 meters above the ground.

How would I work out the speed and therefore time it takes for the weight to fall to the ground?

Also, how would I work out the acceleration?

If you could give me a detailed answer for just one of the weights that would be great.

Thanks
Dominic
 
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Welcome to PF, Dragonetti.
Your question is incomplete. The rate at which the weights drop, in atmosphere, depends upon how that weight is distributed. That's why parachutes work.
Gravitational acceleration at sea level on Earth is 32 ft/sec2. That, again, assumes no noticeable atmospheric drag.
 
Take the equation : x=Vi + 1/2(gt^2).
X = distance
Vi = initial velocity
G = gravitational acceleration (10 m/s^2)
T = time

The mass of the weights will have no effect on the velocity with which the weight hits the ground.
Your initial velocity will be 0 bacause the weight will be let loose from a stationary position, 10 meters above the ground.
Take the time from the moment you let the weight loose 'till it hits the ground.

The velocity with which the weight hits the ground will be obtained by Vf^2=Vi^2 + 2gx.
 
On Earth the estimated acceleration is 9.8 meters per second squared. Weight is not a factor when calculating acceleration and velocity, only resistance being air pressure for example. If you were to have a feather in a vacuumed tube it would fall the same speed as a brick of gold.
Hope that helps.
TM
 
Danger said:
Welcome to PF, Dragonetti.
Your question is incomplete. The rate at which the weights drop, in atmosphere, depends upon how that weight is distributed. That's why parachutes work.
Gravitational acceleration at sea level on Earth is 32 ft/sec2. That, again, assumes no noticeable atmospheric drag.

Hi thanks,
The weights are solid metal.
 
Dragonetti said:
Hi thanks,
The weights are solid metal.

Assuming they're spherical and not a sheet of metal or some other weird shape, it's safe to assume from that height and for those weights, they will all drop at the same time. If you notice any difference in drop times, more than likely it was the experimenter's inaccuracies than the atmospheric drag.
 
Frannas said:
Take the equation : x=Vi + 1/2(gt^2).
X = distance
Vi = initial velocity
G = gravitational acceleration (10 m/s^2)
T = time

In some countries, it is a federal offense to confound capital and minuscule letters representing physical constants or variables (not really, but it can easily bring about confusion).
 
Dr Lots-o'watts said:
In some countries, it is a federal offense to confound capital and minuscule letters representing physical constants or variables (not really, but it can easily bring about confusion).
Punished by putting in the stocks!
 
I always laugh at medicine bottles that claim some number of MG in a pill. An Mg is a metric ton, right?
 
  • #10
There's a 't' missing after the Vi in 'Take the equation : x=Vi + 1/2(gt^2).'
 
  • #11
Forgive my mistakes. I typed that post from my cell phone and can't use the lower case at the beginning of each sentence.
As for the forgotten t after Vi...that is just unforgivable, sorry.
 
  • #12
Frannas said:
Take the equation : x=Vi + 1/2(gt^2).
X = distance
Vi = initial velocity
G = gravitational acceleration (10 m/s^2)
T = time

The mass of the weights will have no effect on the velocity with which the weight hits the ground.
Your initial velocity will be 0 bacause the weight will be let loose from a stationary position, 10 meters above the ground.
Take the time from the moment you let the weight loose 'till it hits the ground.

The velocity with which the weight hits the ground will be obtained by Vf^2=Vi^2 + 2gx.

Hi Frannas,
Thanks for the reply, very helpful
 

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