# Vibration problem

• bikramjit das

#### bikramjit das

vibration problem!

## Homework Statement

Question:There is a fixed end beam PQ. It is carrying a motor M. The motor is unbalanced and when the motor is rotating ,it is making the beam to vibrate with a frequency equal to the speed of the motor. A small mass is kept at point A just above the motor on the beam. it also goes up & down along with the beam . When the motor speed is 120 - 150rpm, the object at A is loosing contact with the beam & is actually dancing on the beam. Determine the amplitude of vibration when the speed of motor is 120 rpm and when 150 rpm . Then calculate the natural frequency of the system.

|---------------------M--------------------|

data may be suitably assumed.

## Homework Equations

can't get any of them

## The Attempt at a Solution

This is a base excitation problem. but the natural frequency is diff. to find. pls help

#### Attachments

• Untitled.png
1.1 KB · Views: 343
Last edited:

The motor is unbalanced and when the motor is rotating ,it is making the beam to vibrate with a frequency equal to the speed of the motor

which speed are we talking about here?

@cupid: u can assume the speed of motor as N. This is equal to the frequency of vibration of beam (base).

i mean ... are we talking about angular speed?

yeah, angular speed...pls solve it quickly, grave need

heyy...some one help me out with this question