Answer:
Road A- dry
Road B- mud
Road C- wet
Explanation:
Surface conditions do affect the ease and speed with which a skateboarder can move, on a muddy surface, the tyres of the skate boards finds it difficult to establish adequate fictional force between the skates trees and the traveling surface. Hence, the muddy surface presents a very slippery travel ground for the skate, hence leading the to skateboarder needing to apply caution.
The speed on a wet surfave is height as the amount of firece that will be applied in other to accelerate is very small. The surface is wet and hence serves as a lubricant between the contact surface.
The dry road also has a high speed but lower than a wet surface, frictional force is high here and this tend to slow the skateboarder down except in sloppy terrains.
The amplitude of a wave corresponds to its maximum oscillation of the wave itself.
In our problem, the equation of the wave is
![y(x,t)= (0.750cm)cos(\pi [(0.400cm-1)x+(250s-1)t])](https://tex.z-dn.net/?f=y%28x%2Ct%29%3D%20%280.750cm%29cos%28%5Cpi%20%5B%280.400cm-1%29x%2B%28250s-1%29t%5D%29)
We can see that the maximum value of y(x,t) is reached when the cosine is equal to 1. When this condition occurs,

and therefore this value corresponds to the amplitude of the wave.