Applying Newton's Laws to Friction: Solving Homework Problems

In summary, the conversation discusses a problem involving finding the magnitude and direction of the total force acting on an object, taking into account friction. Several attempts are made to solve the problem, including calculating the X component of the forces and considering different perspectives. The correct answer is eventually determined to be choice C.
  • #1
Fatima Hasan
319
14

Homework Statement


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Homework Equations


F = ma
Fr = uK * N

The Attempt at a Solution


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My answer is 7 but it is not one of the choices


Thanks in advance[/B]
 

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  • #2
In what direction will the force of kinetic friction act? Don't you have to figure that out before you can determine its components?

Edit: Note that you may be better off starting differently. What is the magnitude of the force from F1 and F2 combined?
 
  • #3
Fatima Hasan said:
F1 = 5 N
F2 = 20N
That does not answer the question.

Let me ask it another way: "Ignoring friction, what is the magnitude of the total force acting on the object?"
 
  • #4
jbriggs444 said:
That does not answer the question.

Let me ask it another way: "Ignoring friction, what is the magnitude of the total force acting on the object?"
to the +ve x-axis
so friction is -ve x-axis
 
  • #5
Fx = F1cos37+F2cos37=20 N
 
  • #6
Fatima Hasan said:
Fx = F1cos37+F2cos37=20 N
What is the magnitude of the total of the two forces? Not just the X component.

Oh... As I understand the problem, we are looking down at the surface of a table from above. Your understanding is that we are looking from the side with one force pulling diagonally up and one pulling diagonally down?
 
  • #7
jbriggs444 said:
What is the magnitude of the total of the two forces? Not just the X component.

Oh... As I understand the problem, we are looking down at the surface of a table from above. Your understanding is that we are looking from the side with one force pulling diagonally up and one pulling diagonally down?
yes

Tried your thought, got wrong answer too
 
Last edited:
  • #8
The "looking down from above" interpretation yields an answer that matches one of the choices.
 
  • #9
jbriggs444 said:
The "looking down from above" interpretation yields an answer that matches one of the choices.
Thanks.Got it . It's choice C
 
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Likes jbriggs444

What is Newton's First Law?

Newton's First Law of Motion, also known as the Law of Inertia, states that an object at rest will remain at rest and an object in motion will remain in motion with a constant velocity unless acted upon by an external force.

What is Newton's Second Law?

Newton's Second Law of Motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This can be represented by the equation F = ma, where F is the force, m is the mass, and a is the acceleration.

What is Newton's Third Law?

Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. This means that whenever one object exerts a force on another object, the second object will exert an equal and opposite force back on the first object.

What is friction?

Friction is a force that opposes the motion of an object. It is caused by the interaction between two surfaces and can be affected by factors such as the roughness of the surfaces, the force pressing the surfaces together, and the type of materials involved.

How does friction affect motion according to Newton's Laws?

Friction affects motion by acting as an external force on objects. This means that it can cause changes in the velocity and acceleration of an object, in accordance with Newton's Second Law. Additionally, friction can also cause an object at rest to remain at rest, as described by Newton's First Law.

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