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Old Nov 19th 2017, 06:49 PM   #21
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Originally Posted by avito009 View Post
So now how can F=ma be true because the formula contains acceleration and in an inertial reference frame there is no acceleration or the acceleration is zero. This is a common doubt we get. Now my explanation is this:

An inertial frame of reference is one in which acceleration can be measured. So what it means is this: Lets take an example: An ball is at rest and you take the ball and throw it horizontally to another person, so initially the body is at rest so acceleration is 0. Now when the ball is thrown it accelerates 3 meters per second. So the force is equal to: say ball has a mass of a kg so F=ma= 1*3= 3 kg m/s^2. So Force is measured when there is acceleration.How?

What this second law states is that initially the body is at rest but later it accelerates but after it accelerates its speed remains constant. From the above example the ball it at rest so acceleration =0. But later it accelerates 3 meters per second and stays at this speed. So this is an inertial reference frame since acceleration is measured and stays constant later.

But if after the ball accelerated and later it decelerated and again it accelerated then newtons second law does not hold and force is not measurable since acceleration is not measurable.

This is in laymans terms, is this correct?
How do you throw a ball horizontally with no vertical component? Is the ball pitcher in deep space floating in space in a space suit? Why does the ball accelerate 3 m/s? When the ball is thrown it is given an initial momentum but while it is travelling through empty space there is no acceleration.

Were you perhaps meaning an object in free fall in a uniform gravitational field?
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Old Nov 21st 2017, 12:25 AM   #22
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Vertical Component.

I am assuming no gravity for sake of simplicity. Thats why I said horizontally but yes it is above the ground. So it is vertically at a height.
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Old Nov 21st 2017, 02:01 AM   #23
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Originally Posted by avito009 View Post
So now how can F=ma be true because the formula contains acceleration and in an inertial reference frame there is no acceleration or the acceleration is zero. This is a common doubt we get.
There is nothing wrong with observing acceleration in an inertial reference frame but acceleration is produced by forces. The observed accelerations are not necessarily zero. It's just that in an inertial frame the observer is not accelerating but other objects may be and these can be measured to be non zero.
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Old Nov 21st 2017, 09:57 AM   #24
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Originally Posted by avito009 View Post
So now how can F=ma be true because the formula contains acceleration and in an inertial reference frame there is no acceleration or the acceleration is zero.

Definition - An inertial frame of reference is a frame of reference in wihch a body which is not subjected to any force will remain at rest or move with constant velocity. Its quite possible for a particle to accelerate an inertial frame if it is subjected to force

That tells you everything you need to know, without reading that article I referenced
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