D because friction will slow it down going up hills (for safety reasons) and you go really fast going down.
Google
Hhhhhggvvvvvvcfvvccvvvfg
The frequency of a wave is a measure of the number of waves that passes through a point per unit of time. It has SI units of s^-1. It is also equivalent to Hertz (Hz). We calculate the frequency of the wave described as follows:
Frequency = 5 waves / 2 s = 2.5 / s or 2.5 Hz
