A point P lies on the axis of a ring of mass M and radius a, at a dist

1.	A point P lies on the axis of a ring of mass M and radius a, at a distance a from its centre C. A small particle starts from P and reaches C under gravitational attraction only. Its speed at C will be(a) √(2GM/a)(b) √(2GM/a (1 - 1/√2))(c) (2GM/a (√2 - 1)) (d) zero
Answer» Correct Answer is: (b) √(2GM/a (1 - 1/√2)) V_P = - GM / (√r² + a²), V_C = - GM/a, 1/2 mv² = m [V_P - V_C].

A point P lies on the axis of a ring of mass M and radius a, at a distance a from its centre C. A small particle starts from P and reaches C under gravitational attraction only. Its speed at C will be(a) √(2GM/a)(b) √(2GM/a (1 - 1/√2))(c) (2GM/a (√2 - 1)) (d) zero

Answer»

Correct Answer is: (b) √(2GM/a (1 - 1/√2))

V_P = - GM / (√r² + a²), V_C = - GM/a, 1/2 mv² = m [V_P - V_C].