1
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

A source of sound emits sound waves at frequency $$f_0$$. It is moving towards an observer with fixed speed $${v_s}$$ ($${v_s},v$$, where $$v$$ is the speed of sound in air.) If the observers were to move towards the source with speed $$v_0$$, one of the following two graphs (A and B) will give the correct variation of the frequency $$f$$ heard by the observer as $$v_0$$ is changed.

COMEDK 2022 Physics - Waves Question 7 English

The variation of $$f$$ with $$v_0$$ is given correctly by

A
graph A with slope $$ = {{{f_0}} \over {(v + {v_s})}}$$
B
graph B with slope $$ = {{{f_0}} \over {(v - {v_s})}}$$
C
graph A with slope $$ = {{{f_0}} \over {(v - {v_s})}}$$
D
graph B with slope $$ = {{{f_0}} \over {(v + {v_s})}}$$
2
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

In which mode of transmission, the heat waves travel along straight line with the speed of light?

A
Thermal radiation
B
Forced convection
C
Natural convection
D
Thermal conduction
3
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

The escape velocity of a projectile on the earth's surface is 11.2 km/s. A body is projected out with thrice this speed. The speed of the body far away from the earth will be

A
22.4 km/s
B
31.7 km/s
C
33.6 km/s
D
None of these
4
COMEDK 2022
MCQ (Single Correct Answer)
+1
-0

Consider a compound slab consisting of two different materials having equal lengths, thickness and thermal conductivities K and 2K respectively. The equivalent thermal conductivity of the slab is

A
$$\sqrt2$$K
B
$$3$$K
C
$$\frac{4}{3}$$K
D
$$\frac{2}{3}$$K
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