# How Do I Calculate Kinetic Friction and Acceleration in These Physics Problems?

• xxxixpats
In summary, the conversation discusses two physics problems. The first one involves finding the coefficient of kinetic friction for a mass sliding down an inclined slide. The second problem involves a man pulling a crate across a level floor and finding the final speed of the crate after being pulled a certain distance. Equations such as F=ukN and F=ma are used to solve these problems.
xxxixpats

## Homework Statement

(1)When mass M is at the position shown, it is sliding down the inclined part of a slide at a speed of 1.95 m/s. The mass stops a distance S2 = 1.85 m along the level part of the slide. The distance S1 = 1.25 m and the angle theta = 35.9 degrees. Calculate the coefficient of kinetic friction for the mass on the surface.

(2)A man pulls a crate of mass 73.0 kg across a level floor. He pulls with a force of 188.0 N at an angle of 31.0° above the horizontal. When the crate is moving, the frictional force between the floor and the crate has a magnitude of 114.0 N. If the crate starts from rest, how fast will it be moving after the man has pulled it a distance of 2.90 m?

## Homework Equations

(1) I'm not really sure how to do 1 at all, I have looked through my book and notes and can't see any solution to the problem
(2) I used the formula Fcos(o)-Uk(mg-Fsin(o))=ma

## The Attempt at a Solution

(2) I used the formula Fcos(o)-Uk(mg-Fsin(o))=ma

I suggest you post this on the physics forum...

Start with the free body diagrams. Once you can do that, the equations you need are F=uN (Frictional force) and F=ma. All other so called formulas (in this context) are simple expressions of these two basic equations.

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