A torque of [tex]$0.12 \, N \cdot m$[/tex] is applied to an egg beater.

(a) If the egg beater starts at rest, what is its angular momentum after 0.65 s?

(b) If the moment of inertia of the egg beater is [tex]$2.5 \times 10^{-3} \, kg \cdot m^2$[/tex], what is its angular speed after 0.65 s?



Answer :

Certainly! Let's break down the problem step by step:

### Part (a): Calculate Angular Momentum

We are given:
- Torque ([tex]\( \tau \)[/tex]) = 0.12 [tex]\( \text{N} \cdot \text{m} \)[/tex]
- Time ([tex]\( t \)[/tex]) = 0.65 [tex]\( \text{s} \)[/tex]

Angular momentum ([tex]\( L \)[/tex]) is given by the product of torque and time:
[tex]\[ L = \tau \cdot t \][/tex]

By substituting the given values:
[tex]\[ L = 0.12 \, \text{N} \cdot \text{m} \times 0.65 \, \text{s} \][/tex]

So, the angular momentum [tex]\( L \)[/tex] is:
[tex]\[ L = 0.078 \, \text{N} \cdot \text{m} \cdot \text{s} \][/tex]

### Part (b): Calculate Angular Speed

We are additionally given:
- Moment of Inertia ([tex]\( I \)[/tex]) = [tex]\( 2.5 \times 10^{-3} \, \text{kg} \cdot \text{m}^2 \)[/tex]

First, find the angular acceleration ([tex]\( \alpha \)[/tex]). Angular acceleration is given by:
[tex]\[ \alpha = \frac{\tau}{I} \][/tex]

By substituting the given values:
[tex]\[ \alpha = \frac{0.12 \, \text{N} \cdot \text{m}}{2.5 \times 10^{-3} \, \text{kg} \cdot \text{m}^2} \][/tex]

So, the angular acceleration [tex]\( \alpha \)[/tex] is:
[tex]\[ \alpha = 48.0 \, \text{rad/s}^2 \][/tex]

Now, to find the angular speed ([tex]\( \omega \)[/tex]) after time [tex]\( t \)[/tex]:
[tex]\[ \omega = \alpha \cdot t \][/tex]

By substituting the values of [tex]\( \alpha \)[/tex] and [tex]\( t \)[/tex]:
[tex]\[ \omega = 48.0 \, \text{rad/s}^2 \times 0.65 \, \text{s} \][/tex]

So, the angular speed [tex]\( \omega \)[/tex] is:
[tex]\[ \omega = 31.2 \, \text{rad/s} \][/tex]

### Summary:

- Angular Momentum: [tex]\( 0.078 \, \text{N} \cdot \text{m} \cdot \text{s} \)[/tex]
- Angular Speed: [tex]\( 31.2 \, \text{rad/s} \)[/tex]