| Assertion (A): | On a rainy day, it is difficult to drive a car or a bus at a high speed. |
| Reason (R): | The value of the coefficient of friction is lowered when the surface is wetted. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | Both (A) and (R) are False. |
A car is moving on a banked road with a radius \(R.\) If \(\theta\) is the banking angle and \(g\) is the acceleration due to gravity, which of the following expressions represents the optimum speed \(v,\) at which the car can navigate the turn without requiring friction?
| 1. | \(v=\sqrt{Rg \mathrm{~tan \theta}}\) | 2. | \(v=\sqrt{Rg \mathrm{~sin \theta}}\) |
| 3. | \(v=\sqrt{Rg \mathrm{~cos \theta}}\) | 4. | \(v=\sqrt{Rg \mathrm{~cot \theta}}\) |
A car is negotiating a curved road of radius R. The road is banked at angle . The coefficient of friction between the tyres of the car and the road is . The maximum safe velocity on this road is
1.
2.
3.
4.
| 1. | \(\dfrac{v^2 w}{R g}\) | 2. | \(\dfrac{v^2 w}{2R g}\) |
| 3. | \(\dfrac{gw v^2}{R}\) | 4. | \(\dfrac{R}{g w v^2}\) |