Answer
0.314 seconds
Work Step by Step
We can use the shape of the cosine graph to find out the time when the weight reaches its maximum height.
Since we are dealing with the negative cosine function, the graph of this function will be the reflection of the cosine graph in the x-axis. Therefore, the graph of this function reaches its maximum height at exactly half the time it takes for one complete oscillation.
Since the time for one complete oscillation is $\frac{\pi}{5}=0.628$ seconds, the time it takes for the weight to reach maximum height is 0.314 seconds.
