Answer:
C. 0.2 Hertz
Explanation:
The frequency of a spring is equal to the reciprocal of the period:

where
f is the frequency
T is the period
For the spring in this problem,
T = 5 s
therefore, the frequency is

The boy’s foot causes the motion. His foot is the one that causes the ball to roll down the hill.
The best way to increase the accuracy of a scientific experiment is to have a detailed plan of action for conducting the experiment. You should also repeat the experiment several times to ensure that you get the same result(s) consistently.<span />
B. Mentally represent their environment