Pushing a box across a horizontal floor

In summary, the man is pushing a box 60 kg along a floor by applying force F in a direction 40 degrees above horizontal. The coefficient of static friction between the box and the floor is .7. If the box is on the verge of moving, the acceleration along the floor will be determined by the coefficient of kinetic friction between the box and the floor.
  • #1
Benny851
16
0

Homework Statement


A man wants to push a cardboard box 60 kg along a floor by applying force F in a direction 40 degrees above horizontal. Coefficient of static friction between box and floor is .7.

a) Determine F if box is on verge of moving.

b) Based on part A, determine acceleration along the floor if coefficient of kinetic friction is 0.32.


Homework Equations





The Attempt at a Solution

 
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  • #2
C'mon, you have to at least try yourself before you ask for help...

If you're having trouble deciding where to start... Start by drawing a diagram of all the forces acting on the block. Write each one as a sum of a horizontal and vertical component.
 
  • #3
The problem is I don't know how to draw the force acting on the box. Is the force coming up from ground or going down onto the box from top left? No picture was supplied with problem
 
  • #4
OK, so please tell me if I am heading in right direction. The equations I have so far are as follows:

1. N = Fsin theta + MG
2. Fcos theta = MsN

Now all I need to do is solve for F and that will be my answer to part A, right?
 
  • #5
Benny851 said:
1. N = Fsin theta + MG
It says 'above horizontal', i.e. partly upwards, not downwards.
2. Fcos theta = MsN

Now all I need to do is solve for F and that will be my answer to part A, right?
Yes.
 
  • #6
which direction is the force acting on the box? I don't get what 'above horizontal means'? I assume the force is pointed downward at the top left corner of the box.
 
  • #7
Hi Benny851! :smile:
Benny851 said:
which direction is the force acting on the box? I don't get what 'above horizontal means'? I assume the force is pointed downward at the top left corner of the box.

No, "above" means the way the force is going to, not coming from …

so the man is pushing upwards against the back of the box at 40° above horizontal. :wink:

(so far as sliding is concerned, the effect should he the same as the more usual case of a rope attached to the front of the box and being pulled at 40° above horizontal)
 

FAQ: Pushing a box across a horizontal floor

What is the force required to push a box across a horizontal floor?

The force required to push a box across a horizontal floor depends on the mass of the box and the coefficient of friction between the box and the floor. The formula to calculate this force is F=μmg, where F is the force, μ is the coefficient of friction, m is the mass of the box, and g is the acceleration due to gravity.

How does the mass of the box affect the force required to push it?

The force required to push a box across a horizontal floor increases with the mass of the box. This is because the weight of the box increases with its mass, and the force required to overcome the weight also increases.

What is the relationship between the coefficient of friction and the force required to push a box?

The coefficient of friction is a measure of the resistance between two surfaces in contact. The higher the coefficient of friction, the greater the force required to push a box across a horizontal floor. This is because a higher coefficient of friction means there is more resistance between the box and the floor.

How does the surface of the floor affect the force required to push a box?

The surface of the floor can affect the force required to push a box in two ways. First, a rougher surface will have a higher coefficient of friction, making it more difficult to push the box. Second, a smoother surface may have less friction, but it can also be more slippery, requiring more force to keep the box moving in a straight line.

Is there a limit to how much force can be applied to push a box across a horizontal floor?

Yes, there is a limit to how much force can be applied to push a box across a horizontal floor. This is because the coefficient of friction can only withstand a certain amount of force before the box starts to slide. This limit is known as the maximum static friction force, and it is equal to the product of the coefficient of friction and the normal force acting on the box.

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