# If theta is considered small in problems

1. May 10, 2012

### M. next

we know when theta is considered small enough, sin(theta) is approximately equal to theta. Ok, the question is what happens to theta dot(the time derivative of theta)?

2. May 10, 2012

### Staff: Mentor

If $\theta$ is small all the time, the time-derivative of $sin(\theta)$ is approximately the time-derivative of $\theta$.

3. May 10, 2012

### M. next

thanks

4. May 10, 2012

### Nabeshin

Another way of seeing the above is that the time derivative of sin is cosine, and when theta is small cosine is approximately equal to one.