Why Does My Pendulum Pin Support Reaction Calculation Differ from 299N?

In summary, the individual has a question regarding a pendulum problem and applied certain steps to solve it. However, the resulting answer was different from the given answer of 299N. Upon further examination, they realized their mistake and confirmed that the method used was correct.
  • #1
cambo86
25
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I've got a similar question to http://www.chegg.com/homework-help/questions-and-answers/pendulum-consists-10-kg-uniform-slender-rod-15-kg-sphere-pendulum-subjected-torque-m-50-n--q2722886 for homework. I applied the same steps I used on my homework question to this problem and I get a different answer to the 299N that they have.

Steps for my solution:
1. Calculate the mass moment of inertia around the pin.
2. Find the centre of mass of the pendulum.
3. With the total mass of the pendulum going through the centre of gravity, I calculated the angular acceleration.

[itex]\sum M = I_{0}\alpha[/itex]
[itex]-M - l_{G}mg cos(45) = I_{0}\alpha[/itex]

4. I calculated the normal and tangential accelerations.
[itex]a_{n} = \omega^{2}l_{G}[/itex]
[itex]a_{t} = \alpha l_{G}[/itex]

5. I used D'Alembert's principle (F - ma = 0) for the tangential forces and Newton (F = ma) for the normal forces. Then I can find the magnitude of forces on pin. (The dotted line arrow in the diagram above is the inertial force for D'Alembert's principle.)

I don't get the 299N stated as the answer in the original question but I can't see a problem with the steps I've gone through.
 
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  • #2
Sorry, I made a mistake in reproducing the answer of 299N. The above method works.
 

FAQ: Why Does My Pendulum Pin Support Reaction Calculation Differ from 299N?

1. What is a pendulum pin support reaction?

A pendulum pin support reaction is the force exerted by a pin or pivot point on a pendulum that allows it to swing back and forth.

2. How is the pendulum pin support reaction calculated?

The pendulum pin support reaction is calculated using the principles of statics and the equations of motion for a simple pendulum. It takes into account the mass of the pendulum, the length of the pendulum arm, and the angle at which it is released.

3. What factors affect the pendulum pin support reaction?

The pendulum pin support reaction is affected by the length of the pendulum arm, the mass of the pendulum, and the angle at which it is released. Other factors such as air resistance and friction may also have a small impact.

4. How does the pendulum pin support reaction relate to the period of oscillation?

The pendulum pin support reaction is directly proportional to the period of oscillation of a pendulum. This means that as the pendulum pin support reaction increases, the period of oscillation also increases.

5. Can the pendulum pin support reaction be used to measure the force of gravity?

Yes, the pendulum pin support reaction can be used to indirectly measure the force of gravity. By measuring the period of oscillation and using the equation for the period of a pendulum, the acceleration due to gravity can be calculated.

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