A car of weight W is on an inclined road that rises by 100 m over a distance of 1 Km and applies a constant frictional force \[\frac{W}{20}\] on the car. While moving uphill on the road at a speed of\[10\text{ }m{{s}^{-1}}\], the car needs power P. If it needs power \[\frac{P}{2}\] while moving downhill at speed v then value of v is:

• A. \[20m{{s}^{-1}}\]
• B. \[5m{{s}^{-1}}\]
• C. \[15m{{s}^{-1}}\]
• D. \[10m{{s}^{-1}}\]