A 4 m long copper wire of cross-sectional area 1.2 cm2 is stretched by a force of 4.8 x 103 N. Young's modulus for copper is Y = 1.2 x 1011 N/m2, the increase in length of the wire is
1.32 mm
0.8 mm
0.48 mm
5.36 mm
A stationary police car sounds a siren with a frequency of 990 Hz. If the speed of sound is 30 m/s, an observer, driving towards the car with a speed of 33 m/s, will hear a frequency of
891 Hz
900 Hz
1089 Hz
1100 Hz
Given that the surface tension of water is 75 dyne/cm, its density 1 g/cc and angle of contact zero, the height to which water rises in a capillary tube of 1 mm diameter is (Take g = 10 m/s2)
9.0 cm
7.5 cm
6.0 cm
3.0 cm
An ideal gas heat engine operates in Carnot cycle between 227°C and 127C. It absorbs 6 x 104 cal of heat at higher temperature. Amount of heat converted into work is
1.2 x 104 cal
2.2 x 104 cal
6.0 x 104 cal
4.8 x 104 cal
Two pendulums of lengths 100 cm and 121 cm start vibrating. At some instant the two are at the mean position in the same phase. After how many vibrations of the longer pendulum will the two be in the same phase at the mean position again?
10
11
20
21
The temperature at which the mean KE of the molecules of gas is one-third of the mean KE of its molecules at 180C is
-122C
-90C
60C
151°C
In which process the rate of transfer of heat is maximum?
Conduction
Radiation
Convection
In all three heat is transferred with the same speed
The gas in a vessel is subjected to a pressure of 20 atm at a temperature 27C. The pressure of the gas in a vessel after one-half of the gas is released from the vessel and the temperature of the remainder is raised by 50C is
8.5 atm
10.8 atm
11.7 atm
17 atm
According to Newton's law of cooling, the rate of cooling of a body is proportional to (Δθ)n, where Δθ is the difference of the temperature of the body and the surroundings, and n is equal to
2
3
4
1
D.
1
According to Newton's law of cooling,
But [ given ]
∴ n = 1
The neutral temperature of a thermocouple is 300°C. What is the inversion temperature, if the temperature of cold junction is l0°C?
590°C
610°C
310°C
290°C