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### Student Question

Postsecondary • 2yr.

I have a physics problem. I can't seem to find a way to solve it.

A cart of mass 500 kg is rolling with a speed of 5 m/s on a railway track. There is very little friction between the tracks and the cart.  You apply a constant force on the cart in the direction opposite to its velocity.  From the moment you start applying the force, the cart moves 30 m before coming to a stop.  What was the approximate magnitude of the force you applied?

Physics

## Explanations (1)

• Explanation from Alloprof

Explanation from Alloprof

This Explanation was submitted by a member of the Alloprof team.

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Team Alloprof • 2yr.

Hi GammaRabbit8261,

First off, you'll need to identify the information given, what you're looking for and the correct formulas to find it. From the problem, we know that the object has a mass of 500kg, an initial speed of 5 m/s, when a force is applied in the opposite direction of the movement, it moves 30 m before stopping. We are looking for the force applied in this case.

We know that we'll need to find a force, thus we know that we will need to find an acceleration. According to Newton's second law, we know that a force is equal to the product of the mass and the acceleration, F = ma. That means that we need to find the acceleration.

To find this acceleration, we need to use the information that is given to us. We know the initial/final speed and the movement of the cart. We can use one of these formulas to find the acceleration:

Once you have the acceleration, you'll simply need to use the mass and Newton's second law to find the force!

I hope that helps and let us know if we can help you with anything else!

Anthony B.