# For the single degree of freedom system in the figure, the mass M rolls among an incline of α. The natural frequency of the system will

1.  Increase as α increases

2.  Decrease as α increases

3.  Be independent of α

4.  Increase initially as α increases and then decreases with further increase in α

4

Be independent of α

Explanation :
No Explanation available for this question

# For the system shown in the given figure, the moment of inertia of the weight w and the bar about the pivot point is I0. The natural frequency of the system is given by . The system will vibrate when

1.  b < ka2/w

2.  b = ka2/w

3.  b > ka2/w

4.  a = 0

4

b < ka2/w

Explanation :
No Explanation available for this question

# Rotating shafts tend to vibrate violently at whirling speeds because

1.  Shaft are rotating at very high speeds

2.  Bearing centre line rotating coincides with the axis

3.  The system is unbalanced

4.  Resonance is caused due to the heavy weight of the rotor

4

Resonance is caused due to the heavy weight of the rotor

Explanation :
No Explanation available for this question

# A machine of 100 kg has a 20 kg rotor with 0.5 mm eccentricity. The mounting springs stiffness 85 kN/m and damping are negligible. If the operating speed is 2π rad/s and the unit is constrained to move vertically, the dynamic amplitude of the machine will be

1.  0.470 * 10-4 m

2.  1.38 * 10-3 m

3.  1.270 * 10-4 m

4.  2.540 * 10-4 m

4

1.38 * 10-3 m

Explanation :
No Explanation available for this question

# Match List-I (force transmissibility) wish List-II (frequency ratio) and select the correct answer using the codes given bellow the List: List-I List-II (A) 1 1. ω/ωn > √2 (B) Less than 1 2. ω/ωn = √2 (C) Greater than 1 3. ω/ωn >> √2 (D) Tending to zero 4. ω/ωn < √2

1.  1          2          3          4

2.  2          1          4          3

3.  2          1          3          4

4.  1          2          4          3

4

2          1          4          3

Explanation :
No Explanation available for this question

# A mass of 1 kg is attached to the end of spring with stiffness 0.7 N/mm. The critical damping coefficient of this system is

1.  1.40 Ns/m

2.  18.522 Ns/m

3.  52.92 Ns/m

4.  529.20 Ns/m

4

52.92 Ns/m

Explanation :
No Explanation available for this question

# A shaft has two heavy rotors mounted on it. The transverse natural frequencies, considering each of the rotors separately, these are 100 cycles/sec and 200 cycle/sec respectively. The lowest critical speed is

1.  5367 rpm

2.  6000 rpm

3.  9360 rpm

4.   12000 rpm

4

5367 rpm

Explanation :
No Explanation available for this question

# A shaft has an attached disc at the centre of its length. The disc has its centre of gravity located at a distance of 2 mm from the axis of the shaft. When the shaft is allowed to vibrate in its natural low-shaped mode, it has frequency of vibration of 10 radians/second. When the shaft is rotated at 300 revolutions per minute, it will whirl with a radius of

1.  2 mm

2.  2.25 mm

3.  2.50 mm

4.  3.00 mm

4

2.25 mm

Explanation :
No Explanation available for this question

# Let S and G be positions of centre of mass and geometric centre is a disc attached to a rotating disc with axis at O. Let the system be resisted by viscous damping. Then at the critical speed, the relative positions of G and S are given by

1.

2.

3.

4.

4

Explanation :
No Explanation available for this question

1.  6 Hz

2.  3π Hz

3.  3 Hz

4.  6π Hz

4