Block sliding down an inclined plane and gravity

In summary, the conversation discusses a problem involving a 5.0kg block sliding down an inclined plane at a 12 degree angle with a coefficient of kinetic friction of 0.310. The frictional force is calculated to be greater than the component of gravity, causing the block to slow down. The net work done by friction and gravity is negative, and it is mentioned that an initial force must have been provided to move the block.
  • #1
tbcreighton
2
0

Homework Statement


There is a 5.0kg block sliding 1.5m down an inclined plane 12 degrees from the horizontal. the coefficient of kinetic friction is 0.310. Whats is the work done on the block by friction and gravity?


Homework Equations


F=ma, W=fd, fk=uk*N


The Attempt at a Solution


So, i calculated the frictional force to be [tex]mgcos(12)\mu_{k}[/tex], but when i found the component force of gravity in the opposite direction ([tex]mgsin(12)[/tex]), i found that the force of friction was bigger than it. I think I am just overlooking something major, but i can't see what i did wrong.
 
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  • #2
You didn't do anything wrong. You're right... the friction is greater than the component of gravity... this means the acceleration is up the plane...

So it is sliding downwards, but slowing down. net work done by friction and gravity will be negative.

Go ahead and calculate the work by friction and gravity.
 
  • #3
DOH! of course. I feel really dumb now. Thanks for your help.
 
  • #4
If I have understood the above correctly, some initial force must have been provided before it moved. That would have imparted the velocity, and the unbalanced force will decelerate it.
 

1. How does the angle of the inclined plane affect the acceleration of a block sliding down?

The angle of the inclined plane affects the acceleration of a block sliding down by changing the force of gravity acting on the block. As the angle increases, the force of gravity pulling the block down the slope also increases, resulting in a higher acceleration. This can be seen through the equation F=mgSinθ, where θ is the angle of the incline.

2. What role does the mass of the block play in its acceleration down an inclined plane?

The mass of the block does not affect the acceleration down an inclined plane. According to Newton's second law of motion, the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Since the force of gravity and the angle of the incline are constant, the mass of the block does not change the acceleration.

3. Can the coefficient of friction impact the motion of a block sliding down an inclined plane?

Yes, the coefficient of friction can impact the motion of a block sliding down an inclined plane. Friction is the force that opposes the motion of an object, and it is affected by the roughness of the surfaces in contact. A higher coefficient of friction will result in a higher force of friction, which will slow down the block's motion down the incline.

4. How can the velocity of a block sliding down an inclined plane be calculated?

The velocity of a block sliding down an inclined plane can be calculated using the equation v = √(2gh), where g is the acceleration due to gravity (9.8 m/s²), h is the height of the incline, and v is the final velocity of the block at the bottom of the incline. This equation assumes no friction or air resistance.

5. What is the difference between a block sliding down a frictionless inclined plane and one with friction?

The difference between a block sliding down a frictionless inclined plane and one with friction is the presence of a force that opposes motion. In a frictionless inclined plane, the block will continue to slide down the slope at a constant velocity, while in a plane with friction, the block's velocity will decrease due to the force of friction. This results in a shorter distance traveled for the block on the incline with friction.

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