Solve the Pendulum Beam Problem with Simple Equations | Homework Help

In summary, the problem involves finding the length of a suspended steel beam using the period equation for a physical pendulum. This requires knowing the moment of inertia and distance to the centre of mass of the beam. The given attempt at a solution is incorrect as it uses the period equation for a simple pendulum, which is not applicable in this case.
  • #1
PhyzicsOfHockey
42
0

Homework Statement



On the construction site for a new skyscraper, a uniform beam of steel is suspended from one end. If the beam swings back and forth with a period of 1.10 s, what is its length?

Homework Equations



T=2*pi*sqroor (L/g)

The Attempt at a Solution



(1.1/(2*3.14))^2*9.81=L

L=.3007m

This is wrong however and I don't understand why.
 
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  • #2
PhyzicsOfHockey said:

Homework Statement



On the construction site for a new skyscraper, a uniform beam of steel is suspended from one end. If the beam swings back and forth with a period of 1.10 s, what is its length?

Homework Equations



T=2*pi*sqroor (L/g)

The Attempt at a Solution



(1.1/(2*3.14))^2*9.81=L

L=.3007m

This is wrong however and I don't understand why.
The period equation you have written is for a simple pendulum with a point mass at the end. You cannot use it for this case, since the mass is uniformly distributed along the beam. You must find or derive the correct formula for this case.
 
  • #3
This is the case of physical pendulum. The gravitational force acts at centre of mass and u can assume a point mass hanging there and then calculate.
 
  • #4
no, you will need the moment of inertia of the steel rod as well
 

1. How does the length of the pendulum affect its period?

The length of the pendulum directly affects its period, which is the time it takes for one complete swing. The longer the pendulum, the longer its period. This can be explained by the equation T = 2π√(L/g), where T is the period, L is the length of the pendulum, and g is the acceleration due to gravity. Therefore, as the length of the pendulum increases, the period also increases.

2. How does the mass of the pendulum affect its period?

The mass of the pendulum does not affect its period. This is because the equation for the period of a pendulum does not contain the mass of the pendulum. Therefore, the period remains the same regardless of the mass of the pendulum.

3. How does the amplitude of the pendulum affect its period?

The amplitude of the pendulum does not affect its period. This is because the period of a pendulum is only dependent on the length of the pendulum and the acceleration due to gravity. The amplitude, which is the maximum angle of swing, does not impact the time it takes for one complete swing.

4. How does air resistance affect the motion of a pendulum?

Air resistance can affect the motion of a pendulum by slowing it down and decreasing its amplitude. This is because as the pendulum swings, it encounters air resistance which acts against its motion. However, for most pendulum beam problems, air resistance is assumed to be negligible and does not significantly affect the motion of the pendulum.

5. How does the angle of release affect the motion of a pendulum?

The angle of release, or the angle at which the pendulum is released from its resting position, does not affect the period of the pendulum. However, it does affect the amplitude of the pendulum's swing. The greater the angle of release, the larger the amplitude of the pendulum's swing will be. This is because the potential energy of the pendulum is converted into kinetic energy as it swings, and a greater angle of release means a greater potential energy to be converted.

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