Torque and center of mass question

In summary, we are given a suspended block with non-uniform density and mass m, suspended by two massless wires against gravity. The left wire is at an angle of phi_1 and the right wire is at an angle of phi_2, while the block has a length of L. Our goal is to find the center of mass. To approach this problem, we consider the tension in the wires and the concept of torque, which is the force measured from a distance. By setting the torques created by the two wires (t_1 and t_2) equal to each other, we can solve for the center of mass (x) using the forces (F_1 and F_2) and the length of the block
  • #1
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We have a block of un-uniform density of mass m suspended by two massless wires, against gravity. The left wire makes an angle phi_1while the right angle makes an angle phi_2. The block has length L. They want me to find the center of mass.
THis is what I've done:
We have tension in the wires. Torque is force measured from a distance. In our case, the two wires create a torque about the center of mass. I find the forces,
F_1 = sin(phi_1)*m*g
F_2 = sin(phi_2)*m*g
And realize that the torques are
t_1 = F_1*x_c_m;
t_2 = F_2*(L - x_c_m)
since they equal another (net torque is zero), i set them t_1 = t_2 and solve for x. However the answer is incorrect and I am told to check my trignometry. My answer is
x = (L sin(phi_2)) / (sin(phi_1)+sin(phi_2))

whatever am i doing wrong?
 
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  • #2
Where do you put your fulcrum?
 
  • #3
my fulcrum is x_cm, or the center of mass of the block from the left side.
 
  • #4
One question... are the wires attached to the ends of the block, you were not clear on that...
 
  • #5
yes they are. the wire making an angle phi_1 is on the left side and the wire making an angle phi_2 is on the right side.
 

1. What is torque?

Torque is a measure of the force that causes an object to rotate around an axis. It is calculated by multiplying the force applied to an object by the distance from the axis of rotation to the point where the force is applied.

2. How is torque related to center of mass?

The center of mass is the point at which an object's mass is evenly distributed. Torque is related to the center of mass because it is the point where the force of gravity acts on an object. The distance from the center of mass to the axis of rotation affects the amount of torque needed to rotate the object.

3. How does the distribution of mass affect torque?

The distribution of mass affects torque because the further away the mass is from the axis of rotation, the greater the torque needed to cause rotation. This is why objects with most of their mass concentrated near the axis of rotation are easier to rotate than those with their mass spread out.

4. Can torque and center of mass be used to determine stability?

Yes, torque and center of mass can be used to determine stability. If the center of mass is located above the base of an object, it will be more stable because the torque caused by gravity will be less likely to cause the object to tip over.

5. How are torque and center of mass used in everyday life?

Torque and center of mass are used in everyday life in activities such as sports, construction, and transportation. Understanding how these concepts work allows us to design and use objects more efficiently and safely. For example, a well-designed bicycle will have its center of mass positioned near the pedals to make it easier to balance and ride.

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