Physics
Column X shows the kind of vibrations and column Y shows their examples.
| X | Y |
|---|---|
| (A) Natural vibrations | (1) A tuning fork when stroked on a rubber pad. |
| (B) Damped vibrations | (2) When a guitarist plucks or strums the guitar strings with his/her fingers. |
| (C) Forced vibrations | (3) When a troop crosses a suspension bridge. |
| (D) Resonant vibrations | (4) A load suspended from a spring. |
Choose the correct pairing:
(a) A—(4) B—(2) C—(3) D—(1)
(b) A—(4) B—(1) C—(2) D—(3)
(C) A—(4) B—(3) C—(1) D—(2)
(d) A—(2) B—(3) C—(4) D—(1)
Answer
A—(4) B—(1) C—(2) D—(3)
Reason
Natural vibrations occur when a body vibrates freely without external force after being disturbed once so a load on a spring will oscillate on its own naturally at its natural frequency.
When a tuning fork is struck, it vibrates but the amplitude decreases gradually due to friction with air or internal resistance, hence damping occurs.
Guitar strings are kept vibrating by external forces (plucking or strumming fingers) so this is an example of forced vibrations.
If the troop's stepping frequency matches the natural frequency of the bridge, resonance occurs.
Related Questions
At resonance, a loud sound is heard because the body vibrating with a large …………… sends forth a large amount of energy in the medium.
- amplitude
- frequency
- wavelength
- time period
The sound box of a musical instrument is so constructed that the air column inside it has a natural frequency …………… that of the string stretched in it.
- greater than
- smaller than
- equal to
- cannot say
(a) Name one factor on which the frequency of sound emitted due to vibration in an air column depends.
(b) How does the frequency depend on the factor stated in part (a)?
State one way of increasing the frequency of a note produced by an air column.