Need Help With Newton's Second Law (Net Force) Problem

In summary, the conversation discusses using Newton's second law to find the weight of a lamp and the tension in a chain. The diagram provided helps with resolving forces into x and y components, and a free body diagram is recommended. It is determined that the weight of the lamp is equal to the y component of the tension force and the tension in the chain is equal to the x component of the tension force. Setting up equations can help solve for the desired values.
  • #1
jillime
7
0

Homework Statement


http://imageshack.us/photo/my-images/534/jillo.jpg/

Okay, so I was given a diagram that looks like the one I linked to above.
This is pretty basic, using Newton's second law to find-

A) the weight of the "lamp"
B) the tension in the chain

The strut is exerting a force of 110 N, the angle between the strut and the ceiling is 55 °.

Thanks so much!

***ALSO the diagram says 11 N, the correct force is 110 N
 
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  • #2
Resolve all the forces into x and y components

Then it should be trivial

Hope this helps
 
  • #3
jacsamell said:
Resolve all the forces into x and y components

Then it should be trivial

Hope this helps

This, but start with a free body diagram as well. They are seriously helpful, and should help you resolve the components.
 
  • #4
I've done a free body diagram. I am still confused as to how to find the weight of the lamp. Does the combined force of the chain and the pull of the lamp have to equal 110 N?
 
  • #5
Try setting up a system. The force of tension in the diagonal string has to compensate for two perpendicular forces since the system is not accelerating.

To answer your question, the chain is completely horizontal, which means the tension in the chain cannot influence the pull of the lamp or visa versa. The chain is balanced horizontally by the horizontal component of the diagonal string.
 
  • #6
jillime said:
I've done a free body diagram. I am still confused as to how to find the weight of the lamp. Does the combined force of the chain and the pull of the lamp have to equal 110 N?

Using some basic trig you can find the x and y components of the 110N that you are given. Then think about how this force is going to be balanced by the chain and lamp weight so it is in equilibrium (net force=0)
 
  • #7
http://imageshack.us/photo/my-images/829/jillf.jpg/

There's my fbd and hopefully correct components, sorry its small.
So does the weight of the lamp have to be equal to the y component and the chain equal to the x component but in the negative direction?

If I seem slow it's because this is my first experience with problems like these.. so bear with me.
 
  • #8
jillime said:
http://imageshack.us/photo/my-images/829/jillf.jpg/

There's my fbd and hopefully correct components, sorry its small.
So does the weight of the lamp have to be equal to the y component and the chain equal to the x component but in the negative direction?

If I seem slow it's because this is my first experience with problems like these.. so bear with me.

Very good. Yes you are correct. The y component of the Tension force in the diagonal string has to be equal to the force of gravity on the lamp, and the x component of Tension force has to be equal to the tension in the chain. Setup your equations and you're done (and can solve for what you're looking for).
 
  • #9
awesome, thanks!
 

Related to Need Help With Newton's Second Law (Net Force) Problem

1. What is Newton's Second Law?

Newton's Second Law, also known as the Law of Acceleration, states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

2. How do you calculate net force?

To calculate net force, you need to know the mass of the object and the acceleration it experiences. Then, you can use the formula F=ma, where F is the net force, m is the mass, and a is the acceleration.

3. Can you give an example of a net force problem?

Sure! Let's say a car with a mass of 1000 kg is accelerating at a rate of 5 m/s^2. What is the net force acting on the car? Using the formula F=ma, we can calculate the net force to be 5000 N.

4. What are the units of net force?

The units of net force are newtons (N). This is because the formula for net force is F=ma, where F is measured in newtons, m is measured in kilograms, and a is measured in meters per second squared.

5. How is Newton's Second Law related to the other laws of motion?

Newton's Second Law is related to the other two laws of motion. It can be thought of as a combination of the other two laws - the First Law states that an object will remain at rest or in motion unless acted upon by a net force, while the Third Law states that for every action, there is an equal and opposite reaction. Newton's Second Law shows how these laws work together to determine the acceleration of an object.

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