Question

In the following waveform, it takes 9 seconds for the wave to pass from point

A to point B.  

      A      B

What is the period of the wave? 

What is the frequency of the wave? 

2. Copy and complete the following table

PrefixAbbrevMultiplierMegaM103Centi10-3n

3. A 1.0 kg mass on a spring is stretched and released. The period of oscillation is measured to be 0.46 s. What is the spring constant?  

4. Describe how you would make a pendulum with a period of 1.0 sec. 

5. (a)What would be the period of a pendulum that is 1.0 m long? 

(b) Imagine you could travel to the moon where the acceleration due to gravity is 1.6 m/s2. What would be the period of a pendulum that is 1.0 m? 

6. (a) A power mower does 9.00 x 105 J of work in 0.500 h. What power does it develop?

(b) How long would it take a 500. W electric motor to do 1.50 x 105 J of work?

Answer 1

The period is wavelength divided by speed:

$$T=\lambda/v.$$

Frequency:

$$f=\frac 1T.$$

3. The equation for period can help us to determine the spring constant:

$$T=2\pi\sqrt{m/k},\\\space\\ k=\frac{4\pi^2 m}{T^2}=187\text{ N/m}.$$

4. Make a simple pendulum. Equation for period is

$$T=2\pi\sqrt{\frac lg},\\\space\\ l=\frac{gT^2}{4\pi^2}=0.25\text{ m}.$$

So, take a string length of 25 cm.

5. (a) The period is

$$T=2\pi\sqrt{\frac lg}=2.01\text{ s}.$$

(b) On the Moon:

$$T=2\pi\sqrt{\frac lg}=4.97\text{ s}.$$

6. (a) Power:

$$P=W/t=500\text{ W}.$$

(b) The time is

$$t=\frac WP=300\text{ s}.$$