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

• 
• 

C.

The fundamental frequency of string

A 200 W sodium street lamp emits yellow light of wavelength 0.6 um. Assuming it to be 25% efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is

• 1.5 x 10²⁰

• 6 x 10¹⁸

• 62 x 10²⁰

• 3 x10¹⁹

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 tangent to the orbit

The horizontal range and the maximum height of a projectile are equal. The angle of projection of the projectile is

• 
• 
• 
• 

B.

Given, R = H

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

• 0.75 m