# Block Slides on Rough Horiz Surface with Pic

• hodgepodge
In summary, a block slides from point A to point B with a force of 2 Newtons acting on it. The distance between A and B is 1.5m and the initial KE at A is 5 joules while the final KE at B is 4 joules. Using the Work-Energy Theorem, the work done by the force of friction can be calculated by subtracting the sum of all other forces from the change in kinetic energy. In this case, the only other force is the friction force, and solving for the unknown work done by friction results in a value of -3.298J.
hodgepodge

## Homework Statement

A block slides on a rough horizontal surface from point A to point B with a force of magnitude 2 Newtons acts on the block between points A and B. Points A and B are 1.5m apart. If the KE of the block at A is 5 joules, and KE at B is 4J, how much work is done on the block by the force of friction as the block moves from A to B

my crude rendering of said block:

http://img69.imageshack.us/img69/2411/30326150.th.png

## Homework Equations

change in E mechanical=Work done by other forces - Force of friction * distance

## The Attempt at a Solution

change in KE = Force * distance + Work done by friction
-1 = 2 cos 40 * 1.5 + Work done by friction
-1 = 2.29813 + Work done by friction
-3.298J = Work done by friction
is this correct?
i got -3.298J

Last edited by a moderator:
hodgepodge said:
change in KE = Force * distance + Work done by friction

This equation is incorrect. The correct equation (Work-Energy Theorem) says

Change in KE = Sum of the work done by all the forces.

How many forces are doing work and what is the work done by each force? Call the unknown work done by friction Wf, write the Work-Energy Theorem correctly and solve for the unknown Wf.

## 1. What is block sliding on a rough horizontal surface?

Block sliding on a rough horizontal surface is a physical phenomenon where a block or object is placed on a rough surface and experiences motion due to the forces acting on it. The roughness of the surface creates friction, which opposes the motion of the block.

## 2. What factors affect block sliding on a rough horizontal surface?

The factors that affect block sliding on a rough horizontal surface include the mass and shape of the block, the roughness of the surface, the angle of the surface, and the force applied to the block.

## 3. How does the roughness of the surface impact block sliding?

The roughness of the surface affects block sliding by creating friction, which opposes the motion of the block. The rougher the surface, the greater the friction, and thus the more force is needed to overcome it and keep the block sliding.

## 4. Can friction be reduced in block sliding on a rough horizontal surface?

Yes, friction can be reduced in block sliding on a rough horizontal surface by using lubricants, such as oil or grease, which create a slippery layer between the block and the surface. This reduces the contact between the two and reduces the amount of friction.

## 5. How can block sliding on a rough horizontal surface be used in real-life applications?

Block sliding on a rough horizontal surface is commonly used in everyday activities such as pushing a heavy object across the floor or using sandpaper to smooth out surfaces. It is also important in engineering and designing machinery that requires sliding components, as friction can cause wear and tear on these parts.

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