Work Done by Incline Plane & Gravity on Block?

In summary, the work done by gravity on the block is positive, even though the incline plane is present. Additionally, the work done by the incline plane is negligible when considering the block's movement.
  • #1
TheNotoriousWM
2
0
Say we have a friction-less inclined plane in the shape of a right triangle, sloping downward to the right. The angle above the horizontal axis is inconsequential for these specific purposes aside from the fact that we know it is inclined above said axis.

We then have a block sliding down (to the right) the plane. My question is about the work done on the block by the incline plane and gravity.

Is the work done by the inclined place on the block considered to be positive, negative, or zero? I think it is zero as what would be considered the normal force has a direction perpendicular to the movement of the block.

I am also hung up on the same question regarding the work done by gravity. It would make sense to think the work by gravity would be positive as that is what moves the block down the inclined plane without outside forces having acted upon it. I just wanted to verify these if anyone could possibly clear things up a bit.

Thanks in advance.

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  • #2
If you lift an object, you are giving it gravitational potential energy.

So, to put it at the top of that incline, it will have gained potential energy.

When it is released, it is losing potential energy, but gaining gravitational kinetic energy.

KE = PE

==================

When it's frictionless, it's best to think of these problems with the equations

KE = [itex]\frac{1}{2}[/itex]mv[itex]^{2}[/itex]

PE = mgh
 
  • #3
TheNotoriousWM said:
Say we have a friction-less inclined plane in the shape of a right triangle, sloping downward to the right. The angle above the horizontal axis is inconsequential for these specific purposes aside from the fact that we know it is inclined above said axis.

We then have a block sliding down (to the right) the plane. My question is about the work done on the block by the incline plane and gravity.

Is the work done by the inclined place on the block considered to be positive, negative, or zero? I think it is zero as what would be considered the normal force has a direction perpendicular to the movement of the block.

I am also hung up on the same question regarding the work done by gravity. It would make sense to think the work by gravity would be positive as that is what moves the block down the inclined plane without outside forces having acted upon it. I just wanted to verify these if anyone could possibly clear things up a bit.

Thanks in advance.

12540n8.jpg
Hello TheNotoriousWM. Welcome to PF !

You are correct on both accounts.
 
  • #4
Thanks for the help all, never hurts to check.
 
  • #5


I can provide a response to your question about the work done by the inclined plane and gravity on the block.

Firstly, let's define work as the transfer of energy from one form to another. In this case, the work done by the inclined plane and gravity would be the transfer of energy to the block as it slides down the plane.

Now, let's consider the work done by the inclined plane. As you correctly stated, the normal force (perpendicular to the movement of the block) does not do any work on the block. This is because the direction of the force is perpendicular to the displacement of the block, and work is only done when the force and displacement are in the same direction. Therefore, the work done by the inclined plane on the block is zero.

Next, let's look at the work done by gravity. Gravity is the force that is causing the block to slide down the inclined plane. As the block moves in the direction of the force, work is being done on the block. Therefore, the work done by gravity is positive.

In summary, the work done by the inclined plane on the block is zero, while the work done by gravity on the block is positive. I hope this helps to clarify any confusion you may have had. Keep exploring and asking questions, that's what being a scientist is all about!
 

1. What is an incline plane and how does it affect work done on a block?

An incline plane is a flat surface that is tilted at an angle. When a block is placed on an incline plane, the force of gravity acts on the block at an angle, which changes the direction of the force. This change in direction affects the amount of work done on the block.

2. How does the angle of the incline plane affect the work done on a block?

The angle of the incline plane affects the work done on a block because it changes the distance the block is moved. The steeper the incline, the greater the distance the block will move, resulting in more work done.

3. What role does gravity play in the work done on a block on an incline plane?

Gravity is the force that acts on the block, causing it to move down the incline plane. This force is what allows work to be done on the block.

4. How is work calculated for a block on an incline plane?

The formula for calculating work on a block on an incline plane is W=Fd, where W is work (in joules), F is the force applied to the block (in newtons), and d is the distance the block is moved (in meters).

5. Does the mass of the block affect the work done on it on an incline plane?

Yes, the mass of the block does affect the work done on it on an incline plane. The greater the mass of the block, the more force is required to move it up the incline plane, resulting in more work being done.

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