# Calculating the Force Required to Move a Crate at Constant Velocity

• moy13
In summary, to find the magnitude of force (Fpush) needed to move a 28.4 kg crate at constant velocity along a level floor, a factory worker must push downward at an angle of 31 degrees below the horizontal. This can be calculated using the equations: sum of Fx = Fpush*cos(31) - (kinetic friction) = 0 and sum of Fy = n - Fpush*sin(31) - mg = 0. The total work done is equal to the change in kinetic energy, which is represented by the equation F dot s = Fscos(31). The coefficient of kinetic friction between the crate and the floor is 0.25. To solve for Fpush, plug
moy13

## Homework Statement

A factory worker pushes a 28.4 kg crate a distance of 4.6 m along a level floor at constant velocity by pushing downward at an angle of 31 degrees below the horizontal. The coefficient of kinetic friction between the crate and floor is 0.25.

What magnitude of force (Fpush) must the worker apply to move the crate at constant velocity?

## Homework Equations

sum of Fx = Fpush*cos(31) - (kinetic friction) = 0
sum of Fy = n - Fpush*sin(31) - mg = 0

total work = K2 - K1 = 0
work = F dot s = Fscos(31)

kinetic friction = mu-sub-k * n

## The Attempt at a Solution

Fpush = (kinetic friction) / cos(31)

and

n = Fpush*sin(31) + mg

I need n, but I can't find it this way, what else can I do?

Thanks for any help.

Last edited:
Solve for Fpush and plug that into the other equation. I'm having trouble with forces myself, but that's what I would do.

Actually FN is equal to mass times gravity. You already have everything else so I think all you have to do is solve.

joseg707 said:
Actually FN is equal to mass times gravity. You already have everything else so I think all you have to do is solve.

I tried keeping n as the mass times gravity, but I get the wrong answer since there is a downward force exerted on the crate by the factory worker.

## 1. What is a force?

A force is a push or pull that can cause an object to accelerate or change its motion. It is a vector quantity, meaning it has both magnitude and direction.

## 2. What is friction?

Friction is a force that opposes the motion of objects that are in contact with each other. It is caused by the roughness of surfaces and can slow down or stop the motion of an object.

## 3. What factors affect the amount of friction?

The amount of friction depends on the roughness of the surfaces in contact, the force pressing the surfaces together, and the type of motion between the surfaces.

## 4. How does friction affect work?

Friction can make it harder to do work because some of the energy put into work is lost as heat due to the frictional force. This means more work must be done to achieve the same result.

## 5. What is work and how is it calculated?

Work is the transfer of energy that results in the displacement of an object. It is calculated by multiplying the force applied by the distance the object moves in the direction of the force: Work = Force x Distance.

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