To solve this problem, let's interpret the given information step-by-step.

1. We know that the point $p$ is on the unit circle. The length of the unit circle's circumference is $2\pi$ (since $C = 2\pi r$ and the radius $r = 1$).

2. The arc from $(1, 0)$ to $p$ is $\frac{1}{5}$ of the unit circle. Therefore, the length of this arc is: $\frac{1}{5} \times 2\pi = \frac{2\pi}{5}$

3. On the unit circle, the radian measure of an angle is equal to the length of the corresponding arc (since the radius is 1). So, the radian measure of the angle from $(1, 0)$ to $p$ is also $\frac{2\pi}{5}$.

Answer

The radian measure of the angle given by the arc from $(1, 0)$ to $p$ is: $\frac{2\pi}{5}$

Would you like further details or have any questions?

Here are some related questions to expand on this concept:

1. What is the degree measure equivalent to $\frac{2\pi}{5}$ radians?
2. How do you convert an arc length to a radian measure in general?
3. What would the arc length be if the angle was $\frac{\pi}{3}$ radians on a unit circle?
4. How does the circumference of the unit circle relate to its radius?
5. How would this problem change if the radius of the circle were different?

Tip: Remember, the radian measure of an angle on the unit circle is equal to the arc length it subtends.