Classical Mechanics: 12N Block on Wall - Will it Move?

In summary, the 1kg wooden block will remain at rest when pressed against a wooden wall by 12N, as the force of gravity is greater than the force of the press in the vertical component. The coefficient of static friction between wood on wood is 0.50 and can only oppose the direction of motion. The maximum available friction is μR and it can only prevent the block from moving, not drive it in either direction. The net force of the block will be zero if the force of friction is equal in magnitude to the force of gravity.
  • #1
Bostonpancake0
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A 1kg wooden block is being pressed against a wooden wall by 12N. If the block is initially at rest will it move upward, downward or remain at rest?



Picture of problem is in link below along with my working out. co-effecient of static friction of wood on wood is 0.50. I have also made static friction and force upward in the y component positive (same direction) and fore of gravity downwards.
 

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  • #2
answer in book says at rest
 
  • #3
Bostonpancake0 said:
A 1kg wooden block is being pressed against a wooden wall by 12N. If the block is initially at rest will it move upward, downward or remain at rest?



Picture of problem is in link below along with my working out. co-effecient of static friction of wood on wood is 0.50. I have also made static friction and force upward in the y component positive (same direction) and fore of gravity downwards.

Don't forget that μR is the maximum available friction - it could always be less.

If the mass was to move up, friction would be acting down.

I would calculate what what happens in the absence of friction, then see if friction can prevent that happening.
 
  • #4
in the absence of friction block moves down as Fg is greater than force of press in the vertical component. And i assumed that static frcition would play a role and oppose the direction of motion thus would act upwards (similiar to that on an incline plane). so adding Fg, static friction and vertical upward force should give me a net force of zero right? if the object was to remain at rest, as stated in answers.
 
  • #5
Bostonpancake0 said:
in the absence of friction block moves down as Fg is greater than force of press in the vertical component. And i assumed that static frcition would play a role and oppose the direction of motion thus would act upwards (similiar to that on an incline plane). so adding Fg, static friction and vertical upward force should give me a net force of zero right? if the object was to remain at rest, as stated in answers.

Zero net force would be nice.

What size would the force of friction have to be to give a net force of zero?

What is the maximum size the friction force can be?

Does that mean it IS possible for friction to prevent motion?

Remember, friction will not drive the block in either direction, it can only prevent the block from moving.
 

1. What is classical mechanics?

Classical mechanics is a branch of physics that deals with the motion of objects and the forces that cause them to move. It is based on Newton's laws of motion and is used to describe the behavior of macroscopic objects.

2. What is a 12N block on a wall?

A 12N block on a wall refers to a block of mass 12 kilograms that is resting on a vertical wall. This situation is often used as an example in classical mechanics problems to demonstrate the principles of static equilibrium.

3. Will the 12N block on a wall move?

In most cases, no. If the block is at rest and there are no external forces acting on it, it will remain in static equilibrium and not move. However, if there is a strong enough force applied to the block or the wall, it may move.

4. How is the force of the block on the wall calculated?

The force of the block on the wall, also known as the normal force, is equal in magnitude but opposite in direction to the force of gravity acting on the block. It is calculated using the formula F = mg, where m is the mass of the block and g is the acceleration due to gravity.

5. How does the angle of the wall affect the block's motion?

The angle of the wall does not affect the block's motion if it is at rest and in static equilibrium. However, if the wall is inclined at an angle, the normal force and the force of gravity will have components in the horizontal direction, which can cause the block to slide down the wall if the angle is steep enough.

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