# Physics

A railroad flatcar is loaded with crates. The coefficient of static friction between the crates and the floor is 0.27. If the train is moving at 59.7 km/hr, in how short a distance can the train be stopped with a constant acceleration without causing the crates to slide?

I have noo idea how to do this. Can someone show me the steps?

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1. friction between the crates and floor

Force= mu*mass*g

But that must equal ma, or m (v^2/(2d))

mu*mass*g= mass*v^2/2d and you are looking for d.

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👨‍🏫
bobpursley
2. How do I find the mass?

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3. A railroad flatcar is loaded with crates. The coefficient of static friction between the crates and the floor is 0.27. If the train is moving at 59.7 km/hr, in how short a distance can the train be stopped with a constant acceleration without causing the crates to slide?

Ok so I understand that mu*mass*g= mass*v^2/2d, and I need to solve for d. But how do I get the mass?

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4. the masses cancel

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