When a mass is rotating in a plane about a fixed point, its angular momentum is directed along

• a line perpendicular to the plane of rotation

• the line making an angle of 45^o to the plane of rotation

• the radius

• the radius

When a string is divided into three segments of length l₁, l₂, and l₃ the fundamental frequencies of these three segments are v₁, v₂, and v₃ respectively. The original fundamental frequency (v) of the string is

• 

• v = v₁ +v₂ +v₃

• 
• 

Two persons of masses 55 kg and 65 kg respectively. are at the opposite ends of the boat. The length of the boat is 3.0 m and weigh 100 kg. The 55 kg man walks to the 65 kg man and sits with him. If the boat is in still water the centre of mass of the system shifts by

• 3.0 m

• 2.3 m

• zero

• zero

The moment of inertia of a uniform circular disc is maximum about an axis perpendicular to the disc and passing through

• B

• C

• D

• D

ABC is an equilateral triangle with O as its centre F₁, F₂ and F₃ represent three forces acting on the sides AB, BC and AC respectively. If the total torque about O zero then the magnitude of F₃ is

• F₁ +F₂

• F₁ - F₂

• F₁ +F₂/2

• F₁ +F₂/2