A source and an observer are moving towards each other with a speed equal to v/2, where v is the speed of sound. The source is emitting sound of frequency n. The frequency heard by one observer will be

 

1.  zero

2.  n

3.  

4.  3n

 

Velocity of sound waves in air is 330 m/s. For a particular sound in air, a path difference of 40 cm is equivalent to phase difference of 1.6π. The frequency of the wave is

 

A particle is executing linear simple harmonic motion of amplitude A. What fraction of the total energy is kinetic when the displacement is half the amplitude

1.  

Two simple harmonic motions are represented by y₁=4sin$\left(4\pi t-\frac{\pi }{2}\right)$ and y₂= 3cos(4πt). The resultant amplitude is

 

1.  7

Three plates of common surface area A are connected as shown in figure. The effective capacitance will be 

 

1.  3ε₀A/d

When 20 J of work was done on the gas, 40 J of heat energy was released. If the initial internal energy of the gas was 70 J, what is the final internal energy?

1.  50 J

2.  -150 J

3.  90 J

4.  110 J

The value of g at a particular point is 9.8 ms^-2. Suppose the earth suddenly shrinks uniformly to half its present size without losing any mass. The value of g at the same point (distance of the point from the centre of earth does not change) will now be

 

1.  9.8 ms^-2

A spherical ball is dropped in a long column of viscous liquid. Which of the following 
graphs represent the variation of 
(i) gravitational force with time 
(ii) viscous force with time 
(iii) net force acting on the ball with time? 

 

1.  Q, R, P

The young’s modulus of a wire of length L and radius r is y newton per square metre. If the length is reduced to  and radius . Its young’s modulus will be

 

1.