# Acceleration On an Incline

1. Feb 5, 2005

### Delonge87

Hi,

Just a quick question that im stuck on. If the mass were increased on a trolley moving downhill, would the acceleration increase?

Since F = Ma....i'd say it would, but just to make sure :P

Thanks

2. Feb 5, 2005

### dextercioby

What are the forces that act on the (growing in mass) body & what's the acceleration...??

Daniel.

3. Feb 6, 2005

### Zaimeen

When the trolley moves down, the following expression gives you the acceleration

$$a = g \sin \theta$$, where $$\theta$$ is the angle of inclination

So, what can you say about the magnitude of the acceleration if you increase the mass?

4. Feb 10, 2005

### arildno

This is a meaningless exercise, since the answer depends on the unspecified direction of the momentum (relative to the trolley) of incoming particles.

5. Feb 11, 2005

### gschjetne

Is it possible that this is one of the lame questions where they suppose the mass would come from nowhere? In that case acceleration to gravity is expressed as $g = \frac{G m_\textit{Earth}}{r^2{}_{Earth} }$, $G = 6.67 \times 10^{-11}$
This doesn't involve the mass of the trolly, acceleration due to gravity is independent of mass.

Last edited: Feb 11, 2005
6. Feb 11, 2005

### freemind

In theory, if the trolley could reach relativistic speeds, then its mass could in fact come from "nowhere"......(just kidding )

7. Feb 11, 2005

### gschjetne

Yeah, I have actually wondered how fast stuff really can go as a result of gravity...I suppose the answer lies in black holes. I did read Stephen Hawking's A Brief History of Time, but that was over a year ago. But now we're getting off-topic...

8. Feb 11, 2005

### ek

If someone were pushing or pulling the trolley in addition to the force of gravity, the acceleration would decrease, as acceleration is inversely proportional to mass. But if it is just gravity acting on the trolley, adding mass will not change the acceleration which will always be gsinx.

Of course if you're taking into account friction, then the acceleration will go down, because friction force is uN, and if you have a greater mass there will be more friction and therefore a lower acceleration.

9. Feb 11, 2005

### xanthym

With only gravity involved, adding mass increases two quantities (F & m) proportionally, and hence acceleration remains constant. When other factors (friction, etc.) affect that proportionality, acceleration will change.

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Last edited: Feb 12, 2005
10. Feb 12, 2005

### VietDao29

Hi,
That's wrong! The accerlation will NOT go down. It is:
$$a = g\times(\sin{\theta} - \mu \times \cos{\theta})$$
$\mu$ is the coefficient of friction.
Viet Dao,

11. Feb 12, 2005

### Chronos

Adding a coeffecient of friction changes the question. Are you looking for a mathematical or real world solution? That is disengenuous. Frankly, I think you are trying to show how brilliant you think you are compared to us pedestrians.

12. Feb 12, 2005

### Chronos

To arildno: We agree on that point. What you did not say speaks volumes.

13. Feb 12, 2005

### VietDao29

Sorry, if I make you think that... But honestly, I am not... I never want to be outstanding here..., and I am not graduated yet. So comaperd to you, I am nothing. I am just a normal man living in a this planet. I know there are a lot of people who are more intelligent than me.
I post that just because they are talking about cases that have friction force. And... is that wrong? Am I wrong?
I am sorry if I ever make you guys think that I am trying to show how brilliant am I. Sorry...
Viet Dao,