How can we improve the accuracy of acceleration calculations?

In summary, the rock's velocity decreases as it falls to the ground, and is equal to the gravitational force times the distance from the center of the Earth.
  • #1
salamander
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Hi! I'm quite new here, and I'm not sure wheter this is to go here or in the math section, so I'll just post it here since i guess nobody really care anyway.

I've been thinking of this for a while, but I can't seem to get it right. (I'm not that good at maths but I'm learning.)

Concider dropping a rock from a rather high altitude down to the ground. Now, using Newtonian theory, find an expression for the rocks' velocity as a function of time, that includes the fact that the gravitational attraction must become greater as the distance to Earth shrinks.

Can somebody give me a hint?

I know g=MG/r^2
What confuses me is how to integrate time in this expression,
since r=r0-gt^2/2

Finally, I don't know why but i just like these guys:
 
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  • #2
You need to set up a differential equation relating the distance from the Earth to the acceleration and solve it.
 
  • #3
Letting r be the distance from the center of the earth,
[tex]m\frac{d^2r}{dt^2}= \frac{-GmM}{r^2} [/tex]

That's a non-linear differential equation but we can use the fact that t does not appear explicitely in it: Let v= dr/dt. Then (chain rule):
[tex]\frac{d^2r}{dt^2}= \frac{dv}{dt}= \frac{dr}{dt}\frac{dv}{dr}= v\frac{dv}{dr}[/tex]
so the differential equation becomes
[tex]v\frac{dv}{dr}= \frac{-GM}{r^2}[/tex] and then separate:
[tex]v dv= -GM \frac{dr}{r^2}[/tex]. Integrating:
[tex]\frac{1}{2}v^2= \frac{GM}{r}+ C[/tex].

(Notice that that first integral is the same as
[tex]\frac{1}{2}v^2- GM/r= C [/tex], conservation of energy, since the first term is kinetic energy and the second potential energy.)

That is the same as [tex]v= \frac{dr}{dt}= \sqrt{2\frac{GM}{r}+ C}[/tex] which is also integrable. You can use the fact that GM/r02= g (r0 is the radius of the earth) to simplify.
 
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FAQ: How can we improve the accuracy of acceleration calculations?

What is "More accurate acceleration"?

"More accurate acceleration" refers to the ability to measure changes in an object's velocity over time with a high level of precision. This can be achieved through various scientific methods and technologies.

Why is accurate acceleration important in scientific research?

Accurate acceleration measurements are crucial in scientific research because they provide valuable data about the movement and behavior of objects. This information can be used to understand and predict natural phenomena, as well as to design and improve technologies.

How is acceleration measured?

Acceleration is typically measured using a device called an accelerometer, which can detect changes in an object's speed and direction of motion. Accelerometers use various technologies, such as piezoelectric crystals or microelectromechanical systems (MEMS), to accurately measure acceleration.

What factors can affect the accuracy of acceleration measurements?

There are several factors that can affect the accuracy of acceleration measurements, such as external forces (e.g. friction, air resistance), improper calibration of the measuring device, and human error. It is important to carefully control and account for these factors when conducting experiments involving acceleration.

How can accuracy in acceleration measurements be improved?

To improve accuracy in acceleration measurements, scientists can use more advanced and precise measurement devices, calibrate their equipment properly, and carefully control experimental conditions. Collaborating with other experts and conducting multiple trials can also help to increase the accuracy of results.

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