**Example 5**

What is the **frequency** of a logitudinal wave if the period is 0.2s?

**Answer**

Use the equation** f=1/t**

f=1/0.2 = 5m/s

**Example 6**

If the distance from crest to crest is 16cm and the period is 0.2s, what is the **speed** of the oscillation in IB physics curriculum?

**Answer**

Use the equation** v=fλ**

v= 1/0.2 *0.16

v = 5*0.16 = 0.8m/s

**Example 7**

Explain why the magnitude of the tension in a string at the midpoint of an oscillation is **greater than** the weight of the pendulum bob.

**Answer**

The pendulum bob accelerates towards the **centre** of its circular path, so there is an upwards force. This **adds to tension** produced by weight.

**Example 8**

What is the **shape** of an amplitude frequency graph when the oscillation is lightly damped?

**Answer**

Similar to the graph below:

**Example 9**

What is meant by **resonance** with reference to the previous question?

**Answer**

In IB physics, resonance is when a particle is forced to oscillate at its **natural frequency**, it is the **opposite** to damping shown above as the amplitude usually greatly increases or is the maximum.

**Example 10**

How would the graph in question 8 change if the pendulum was** immersed in water**?

**Answer**

The immersion of water would cause the oscillation to be heavily damped. Therefore, there would be a **lower amplitude** everywhere on the graph; with a **much broader** resonance peak and the maximum moves to the** left** on the graph.

End of this topic!

Drafted by Gina