NEETPhysicsLaws of Motion
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): In a 'death well' (a vertical cylindrical wall used for motorcycle stunts), a heavier motorcyclist requires a significantly greater minimum speed to prevent slipping downwards compared to a lighter motorcyclist. Reason (R): The normal reaction force provided by the wall of the death well is directl
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is true but (R) is false
- D(A) is false but (R) is true
Correct answer
D. (A) is false but (R) is true
Step-by-step solution
For a motorcyclist in a death well, the normal reaction N provides the necessary centripetal force: N = mv^2 R . For a given speed v and radius R , the normal force is directly proportional to the mass m . Hence, Reason (R) is true. The frictional force f acts upwards to balance the weight: f = mg . For the motorcyclist not to slip downwards, f N mg ( mv^2 R ) . The mass m cancels out from both sides, giving the condition for minimum speed as v_ min = gR . Since the minimum speed is independent of the mass, a heavi