Physics-
General
Easy
Question
A train has just complicated a U-curve in a track which is a semicircle. The engine is at the forward end of the semi circular part of the track while the last carriage is at the rear end of the semicircular track. The driver blows a whistle of frequency 200 Hz. Velocity of sound is 340 m/sec. Then the apparent frequency as observed by a passenger in the middle of a train when the speed of the train is 30 m/sec is
- 209 Hz
- 288 Hz
- 200 Hz
- 181 Hz
The correct answer is: 200 Hz
The situation is shown in the fig.
Both the source (engine) and the observer (Person in the middle of the train) have the same speed, but their direction of motion is right angles to each other. The component of velocity of observer towards source is 
and that of source along the time joining the observer and source is also . There is number relative motion between them, so there is no change in frequency heard. So frequency heard is 200 Hz.
Related Questions to study
Maths-
Let 
and 
then the sum 
is equal:
Let and then the sum is equal:
Maths-General
Maths-
Let 
be a function defined by f(x) = log(logx)) the base of the logarithm being e. Then
Let be a function defined by f(x) = log(logx)) the base of the logarithm being e. Then
Maths-General
Maths-
Range of the function 
is
Range of the function is
Maths-General
Maths-
If graph of the function y = f(x) is symmetrical about the line x = 1, then for any real number α
If graph of the function y = f(x) is symmetrical about the line x = 1, then for any real number α
Maths-General
Maths-
If 
then the number of solutions of the equations 
is
If then the number of solutions of the equations is
Maths-General
Maths-
Let 
be a function which satisfies 
for 
can be
Let be a function which satisfies for can be
Maths-General
Maths-
Let 
If 
then the maximum value of 
is equal to
Let If then the maximum value of is equal to
Maths-General
Physics-
Three sound waves of equal amplitude have frequencies (v-1), v,(v+1) . They superpose to give beat. The number of beats produced per second will be
Three sound waves of equal amplitude have frequencies (v-1), v,(v+1) . They superpose to give beat. The number of beats produced per second will be
Physics-General
Physics-
The period of a wave is 360ms-1 and frequency is 500 Hz. Phase difference between two consecutive particals is 60, then path different between them will be
The period of a wave is 360ms-1 and frequency is 500 Hz. Phase difference between two consecutive particals is 60, then path different between them will be
Physics-General
Physics-
The equation 
, where the symbols carry the usual meaning and a, T and 
ate positive, represents a wave of
The equation , where the symbols carry the usual meaning and a, T and ate positive, represents a wave of
Physics-General
Physics-
The identical square rods of metal are welded end to end as shown in figure, 
cal of heat flow through this combination in 4 min. If the rods were welded as shown in figure, the same amount of heat will flow through the combination in
The identical square rods of metal are welded end to end as shown in figure, cal of heat flow through this combination in 4 min. If the rods were welded as shown in figure, the same amount of heat will flow through the combination in
Physics-General
Physics-
22 g of carbon dioxide at 27
is mixed in a closed container with 16 g of oxygen at 37. If both gases are considered as ideal gases, then the temperature of the mixture is
22 g of carbon dioxide at 27 is mixed in a closed container with 16 g of oxygen at 37. If both gases are considered as ideal gases, then the temperature of the mixture is
Physics-General
Physics-
A small sphere carrying a charge 
is hanging in between two parallel plates
by a string of length 
. Time period of pendulum is 
. When parallel plates are
charged, the time period changes to 
The ratio 
is equal to
A small sphere carrying a charge is hanging in between two parallel plates
by a string of length . Time period of pendulum is . When parallel plates are
charged, the time period changes to The ratio is equal to
Physics-General
Physics-
Two springs are joined and attached to a mass of 16 kg. This system is then suspended vertically from a rigid support. The spring constant of the two springs are 
respectively. The period of vertical oscillations of the system will be
Two springs are joined and attached to a mass of 16 kg. This system is then suspended vertically from a rigid support. The spring constant of the two springs are respectively. The period of vertical oscillations of the system will be
Physics-General
Physics-
A mass of 2.0 kg is put on a flat pan attached to a vertical spring fixed on the ground as shown in the figure. The mass of the spring and the pan is negligible. When pressed slightly and released the mass executes slightly and released the mass executes a simple harmonic motion. The spring constant is 
. What should be the minimum amplitude of the motion, so that the mass gets detached from the pan? (Take g=10 
)
A mass of 2.0 kg is put on a flat pan attached to a vertical spring fixed on the ground as shown in the figure. The mass of the spring and the pan is negligible. When pressed slightly and released the mass executes slightly and released the mass executes a simple harmonic motion. The spring constant is . What should be the minimum amplitude of the motion, so that the mass gets detached from the pan? (Take g=10 )
Physics-General
