# Fbd problems using Newtons second law

• agentlxl
In summary, the question is asking for the coefficient of kinetic friction between a wooden crate and the floor given a horizontal force of 30.0 N used to slide the crate at a constant velocity. Using Newton's first law, we know that the sum of forces is 0 when a body is at rest or moving at a constant velocity. Therefore, the friction force acting to the left must be equal to the applied force to the right. By relating the friction force to the coefficient of kinetic friction and the normal force, which is the weight of the crate, we can solve for the coefficient. It is important to not give up and continue working through the problem.
agentlxl
(If you use a horizontal force of 30.0 N to slide a 12.0kg wooden crate across a floor at a constant velocity, what is the coefficient of kinetic friction between the crate and the floor?)
PLZ HELP AHHHHH ITS DUE TMRW SO PLZ HELP

agentlxl said:
(If you use a horizontal force of 30.0 N to slide a 12.0kg wooden crate across a floor at a constant velocity, what is the coefficient of kinetic friction between the crate and the floor?)
PLZ HELP AHHHHH ITS DUE TMRW SO PLZ HELP
This is actually Newton 1...sum of forces = 0 when a body is at rest or moving at constant velocity. So 30N to the right must be balanced by the friction force acting left. Calculate the magnitude of the friction force. Then how would you relate this force with u_k and the Normal force?

listen i don't know anything my teacher just tells us to do it but doesn't explain so yeah that's my problem but thnx for answering

agentlxl said:
listen i don't know anything my teacher just tells us to do it but doesn't explain so yeah that's my problem but thnx for answering
Don't be a quitter! You've got 30N on the crate to the right, and since the block is moving at constant velocity (not accelerating), Newton and Phanthom say that there must be a 30N force acting on it to the left. That's the only way the net force will add to 0, and that force to the left must be the friction force. And since friction force = (friction coefficient)(Normal force), and since Normal force is just the crate's weight, where weight = mg and where g = 9.8m/s/s, solve for the friction coefficient. I'm sure teach told you that. Now come on, chug it out.

## 1. How do I apply Newton's second law to FBD problems?

To apply Newton's second law to FBD (free body diagram) problems, you need to first identify all the forces acting on the object in question. This includes both external forces, such as gravity or friction, and internal forces, such as tension or normal force. Then, use the formula F = ma (force equals mass times acceleration) to calculate the net force acting on the object. This net force will determine the object's acceleration.

## 2. What is a free body diagram and why is it helpful in FBD problems?

A free body diagram is a visual representation of all the forces acting on an object. It is helpful in FBD problems because it allows you to clearly see and understand the different forces at play, making it easier to apply Newton's second law and solve the problem correctly. It also helps to avoid any mistakes or confusion in identifying the forces involved.

## 3. Can Newton's second law be used for objects in motion as well as objects at rest?

Yes, Newton's second law can be applied to both objects in motion and objects at rest. In fact, it is often used to determine the motion of an object based on the forces acting on it. The only difference is that for objects at rest, the acceleration is equal to zero, so the formula becomes F = 0.

## 4. What is the difference between mass and weight in FBD problems?

Mass and weight are often used interchangeably, but they are actually two different concepts. Mass refers to the amount of matter in an object, while weight refers to the force of gravity acting on that object. In FBD problems, mass is used to calculate the object's inertia (resistance to change in motion), while weight is used to calculate the force of gravity acting on the object.

## 5. Can FBD problems using Newton's second law be applied to all types of forces?

Yes, FBD problems using Newton's second law can be applied to all types of forces, including gravitational, frictional, normal, and applied forces. The key is to clearly identify and understand the forces involved and use the appropriate formula to calculate the net force and resulting motion of the object.

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