Chapter 18 Exercise

No 1. Look at the following figure of a pendulum. A motion of 2 vibrations is                   shown as the following successive motion......

           Answer: 1-2-3-2-1-2-3-2-1




No 3.Look at the following figure of a spring. If the spring moves as a-b-c-b-a-b-c-b-a, its motion performs . . . .
Answer: 2 full vibrations






No 5. If 120 vibrations happen in 30 seconds, the correct statement  is . . . .
Answer: The period of the vibration is 1/4 seconds
             P= T÷N
           =30÷120
           =1/4

No 6. A period of a swing is 20 seconds. In every minute, the pendulum will perform........
Answer: 60÷20= 3 swings

No 7. Look at the figure of a ruler that is placed on a table. If in 1/4 seconds the ruler moves in the b-c-b-a-b-c-b pattern, period of the vibration made by the ruler is . . . .

Answer:P=t÷n
            P= 1/4 ÷ 1 1/2 or 3/2
            P= 1/4 x 2/3
            P= 2/12= 1/6 seconds

No 9.  A pendulum performs swings with a frequency of 10 Hz. The number of vibrations that it can make within 5 minutes is . . . .
Answer: 10Hz= 10 vibrations in one second
             = 10 x 300 seconds (from the 5 minutes)
             = 3000 vibrations