Friction Newton's Second Law of Motion

[maxon1017]

Science howework

A crate rests on a horiontal floor. Only gravity and the support force of the floor act on it. A slight pull P is exerted on the crate, not enough to move it. A force of friction f now acts on it.

is f, less than, equal, or greater than P?

is the net force on the crate zero or greater than zero?

P is increased until the crate begins to move. it is pulled at a constant velocity across the floor.

f is: less than, equal to or greater than P?

is the net force on the crate zero, less than or greater than zero?

P is further increased and is now greater than friction f.

is the net force on the crate zero, less than or greater than zero?

 

[Deeviant]

Science howework

A crate rests on a horiontal floor. Only gravity and the support force of the floor act on it. A slight pull P is exerted on the crate, not enough to move it. A force of friction f now acts on it.

is f, less than, equal, or greater than P?

is the net force on the crate zero or greater than zero?

P is increased until the crate begins to move. it is pulled at a constant velocity across the floor.

f is: less than, equal to or greater than P?

is the net force on the crate zero, less than or greater than zero?

P is further increased and is now greater than friction f.

is the net force on the crate zero, less than or greater than zero?

First of all, there is a homework help area of these forums, yet, even there people like to help flesh out your knowledge of the theory behind the questions allowing you to find the answer yourself rather then to answer the questions themselfs.

But to help you out, let me ask you a few questions..

If something is not accelerating, would that be a good indication that the net force acting on it would be zero?(yes)

If the net force is zero, and there is a force applied to the crate, what do you think the force of friction would have to be to counteract it?

If you can understand my first two questions, you can answer all four of the questions in your homework.

 

[Graeme Robinson]

In this scenario, the force of friction (f) is equal to the applied force (P) when the crate is at rest, as the crate is not moving. This is because according to Newton's Second Law of Motion, an object at rest will remain at rest unless acted upon by an unbalanced force. The net force on the crate is also equal to zero, as the forces acting on the crate are balanced.

When P is increased and the crate begins to move at a constant velocity, the force of friction (f) is still equal to the applied force (P). However, the net force on the crate is now greater than zero, as there is a slight unbalanced force causing the crate to move.

When P is increased even further and becomes greater than the force of friction (f), the net force on the crate is now greater than zero. This is because the applied force (P) is now larger than the opposing force of friction (f), causing an unbalanced force and resulting in the crate accelerating in the direction of the applied force.

In summary, the force of friction (f) is equal to the applied force (P) when the crate is at rest and when it is moving at a constant velocity. However, when the applied force becomes greater than the force of friction, the net force on the crate is greater than zero and the crate will accelerate in the direction of the applied force.