- #1

sylent33

- 39

- 5

- Homework Statement
- A box weighing 5kg stands on a board (coefficient of static friction μH = 0.7 and coefficient of sliding friction μG = 0.55). At what angle does the box slide? How big is the acceleration?

- Relevant Equations
- $$ μH = tan(\alpha) $$

Hello! So the way I have tried to solve this problem is the following;Since it is an inclined plane and the cofficient of static friction is known, getting to the angle at which the box starts sliding is the following

##μH = \frac {sin (\alpha)} {cos(\alpha)} = μH = tan(\alpha) ##

## \alpha = tan(0,7)##

## \alpha = 0,012 (degrees) ##

Now for the acceleration I thought of this;

First I would need to find the force that is pulling the object downhill; I did that like this

## F_d = m * g * sin(\alpha)##

## F = 0,0104 N ##

Than I would have to find friction force, that is "opposing" the downhill force;

## F_r = m * g * cos(\alpha)##

## F = 34,33 N ##

Now the problem here is pretty obvious. According to my calculation the box shouldn't be even moving, it should be standing still. Which has to mean one of three things; 1) My calculation of the angle was wrong 2) My calculation of the forces was wrong 3) My entire interpretation of the problem was wrong.

Would anyone be able to assist me? Kind Regards.

##μH = \frac {sin (\alpha)} {cos(\alpha)} = μH = tan(\alpha) ##

## \alpha = tan(0,7)##

## \alpha = 0,012 (degrees) ##

Now for the acceleration I thought of this;

First I would need to find the force that is pulling the object downhill; I did that like this

## F_d = m * g * sin(\alpha)##

## F = 0,0104 N ##

Than I would have to find friction force, that is "opposing" the downhill force;

## F_r = m * g * cos(\alpha)##

## F = 34,33 N ##

Now the problem here is pretty obvious. According to my calculation the box shouldn't be even moving, it should be standing still. Which has to mean one of three things; 1) My calculation of the angle was wrong 2) My calculation of the forces was wrong 3) My entire interpretation of the problem was wrong.

Would anyone be able to assist me? Kind Regards.