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Complete the following by choosing the correct answers from the bracket:
One end of a plastic foot ruler is held tightly at the edge of a table and the other end is plucked. Name the vibrations produced in the ruler.
Now the ruler is pushed inside partially and plucked again from its free end. State with a reason whether the frequency of vibration increases or decreases.
Two persons A and B are standing in front of a cliff in the same line 170 m apart as shown in the diagram. Person B fires the gun and hears the echo in 3 s. Then the person A standing in front of the person B fires the gun. (The speed of sound in air is 340 m/s.)
Calculate the minimum distance needed in water to hear the echo. (Speed of sound in water is 1500 ms⁻¹. Persistence of hearing is 0.1 s.)
The graph shows load against effort for a lever with load and effort on the same side of the fulcrum.
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