When the two waves y1 = a sin ωt and y2 = a cos ωt are superimposed, then resultant amplitude is
a
2a
C.
Given, y1 = a sin ωt .... (i)
and y2 = a cos ωt
⇒ y2 = .... (ii)
From Eqs. (i) and (ii), we get
a1 = a , a2 = a , =
Hence, resultant amplitude
A train moves towards a stationary observer with speed 34 ms-1 . The train sounds a whistle and its frequency registered by the observer is v1 , If the train's speed is reduced to 17 ms-1, the frequency registered is v2. If the speed of sound is 340 ms-1 , then the ratio v1 /v2 is
2
Two vibrating strings of the same material but lengths L and 2 L have radii 2r and r respectively. They are stretched under the same tension. Both the strings vibrate in their fundamental modes, the one of length L with frequency v1 and the other with frequency v2 . The ratio v1 / v2 is
2
4
8
1
The temperature, at which centigrade and Fahrenheit scales give the same reading, is
- 40°
40°
- 30°
30°
A brass rod of length 500 mm and diameter 3 mm is joined to a steel rod of same length and diameter at 50°C. If the coefficients of linear expansion of brass and steel are 2.5 x 10-5 ° C-1 and 1.25 x 10-5 ° C-1 , then change in length of the combined rod at 200°C is
2.4 mm
2.8 mm
3.2 mm
3.6 mm
A copper block of mass 4 kg is heated in a furnance to a temperature 425°C and then placed on a large ice block. The mass of ice that will melt in this process will be (Specific heat of copper = 500 J kg-1 ° C-1 and heat of fusion of ice = 336 kJ kg-1 )
0.5 kg
1 kg
1.5 kg
2.5 kg
A block of ice at - 10°C is slowly heated and converted to steam at 100°C. Which of the following curves represents this phenomenon qualitatively ?
The pressure and density of a diatomic gas change adiabatically from (P1 , ρ1) to (P2 , ρ2) . If , then should be
16
32
64
128
One mole of an ideal gas at an initial temperature of T K does 6R joules of work adiabatically. If the ratio of specific heats of this gas at constant pressure and at constant volume is 5/3, then final temperature of the gas will be
(T − 4) K
(T + 4) K
(T − 2.4)K
(T + 2.4) K
In which mode of transmission, the heat waves travel along straight line with the speed of light?
thermal radiation
forced convection
natural convection
thermal conduction