Applying Newton's Laws and solving multiple object system question

In summary, the problem involves a 3.00-KG mass and a 10.0-KG mass attached to opposite ends of a massless cord, which is strung over a frictionless pulley. The question asks for the acceleration of the two-mass system and the tension in the cord. By drawing a free body diagram and setting up force equations for each body separately, the correct solutions can be found. The acceleration can be calculated by using the force due to gravity of the system and the tension in the cord can be found using the acceleration.
  • #1
Allen93
12
0

Homework Statement


A 3.00-KG mass and a 10.0-KG mass are attached to opposite ends of a massless cord which is strung over a frictinoless pulley.
a) What is the acceleration of the two-mass system?
b) What is the tension in the cord?


Homework Equations



F = net forces
Fg = force due to gravity
a = acceleration
m = mass
* = times (multiply)
g = gravity

Fg = m*g
F = ma


The Attempt at a Solution


I tried to draw a free body diagram of the two objects as one system, subtracting the least massive object from the most massive object (10 kg minus 3 kg). I then found the Fg of the system and used it to find the acceleration, then found the tension force using the acceleration found. According to the answer key, I am off, could anyone please show me the light?
 
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  • #2
Once you draw the free body diagram, write down force equation (net force = mass*acceleration) for each of the bodies, separately. Then you can solve for acceleration.
 
  • #3
Welcome to PF

please can you post your FBD's?

just a rough drawing will work
 
Last edited:
  • #5
i know what is atwood machine and i understood he ques.

i just want to make sure that is FBD's are right
 
  • #6
Ahh I'm sorry, I thought it's the OP asking for FBD. :zzz:
 
  • #7
cupid.callin said:
Welcome to PF

please can you post your FBD's?

just a rough drawing will work
I apologize for replying so late but here's the FBD.
 

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  • #8
Sourabh N said:
Once you draw the free body diagram, write down force equation (net force = mass*acceleration) for each of the bodies, separately. Then you can solve for acceleration.

Thank you!
I reworked the problem and set it up your way and I found the correct solution.
Thank you guys, it was really helpful.
 

FAQ: Applying Newton's Laws and solving multiple object system question

What are Newton's Laws of Motion?

Newton's Laws of Motion are three physical laws that describe the behavior of objects in motion. The first law states that an object will remain at rest or in uniform motion unless acted upon by an external force. The second law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. The third law states that for every action, there is an equal and opposite reaction.

How do I apply Newton's Laws to solve a multiple object system question?

To solve a multiple object system question, you must first identify all the forces acting on each object in the system. Then, you can use Newton's second law (F=ma) to calculate the net force and acceleration of each object. Finally, you can use these values to determine the motion of the objects in the system.

3. Can I use Newton's Laws to solve problems in both one and two dimensions?

Yes, Newton's Laws can be applied to solve problems in both one and two dimensions. In one dimension, you only need to consider forces acting in a single direction. In two dimensions, you must consider forces acting in both the x and y directions and use vector math to solve the problem.

4. What is the difference between static and kinetic friction?

Static friction is the force that must be overcome to start an object moving, while kinetic friction is the force that opposes the motion of an object. The force of static friction is typically greater than kinetic friction, but both depend on the type of surfaces in contact and the normal force.

5. Are there any real-life applications of Newton's Laws?

Yes, Newton's Laws have many real-life applications. For example, they are used in the design of cars and airplanes, in predicting the motion of planets and satellites, and in sports such as soccer and basketball. They are also used in everyday situations, such as pushing a shopping cart or riding a bicycle.

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