# Questions tagged [acceleration]

The rate of change of velocity of a body per unit of time.

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### Which clock is the fastest inside an accelerating body?

The picture shows an accelerating spaceship with two clocks inside it. It is so far away from all other bodys that gravity is of no importance. Will the bottommost clock be slower than the topmost ...
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### When photons are emitted, do they accelerate to reach the speed of light? [duplicate]

Photons are considered mass-less particle with a specific velocity but according to the electromagnetic theory, a photon is considered to have both energy and momentum. So what happen when they are ...
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### Truck moving uphill, object suspended from ceiling, determine acceleration [closed]

A truck is moving with constant acceleration $a$ up a hill that makes and angle $\phi$ with the horizontal. An object of mass $m$ is suspended from the ceiling of the truck by a light cord. If the ...
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### Acceleration is zero, for non-zero net force

I understand a problem like this has already been asked, but I have not found an answer that makes it clear. A force is applied to a box on a table(lets ignore friction), and the box moves with some ...
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### What is wrong with considering the Atwood machine as a system?

I am confused about a method used in the following problem. There is an arrangement as shown below. The surface is smooth, and the pulleys are light. We have to find the acceleration $a_0$ of $m_1$. ...
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### Acceleration ratio

Can anyone please explain why: $$a_1=a_2\tan\alpha$$ We have 2 same cubes placed on a platform, between them there is a wedge which is pushing the cubes in opposite directions. The hard part of the ...
If a point mass has some accelerations $\mathbf{a_1}$ and $\mathbf{a_2}$, why is mathematically true that the "total" acceleration is $\mathbf{a}= \mathbf {a_1}+\mathbf {a_2}$?