Thermal Properties of Matter-Quiz-12

 

THERMAL PROPERTIES OF MATTER QUIZ-12

Dear Readers,

JEE Advanced Physics Syllabus can be referred by the IIT aspirants to get a detailed list of all topics that are important in cracking the entrance examination. JEE Advanced syllabus for Physics has been designed in such a way that it offers very practical and application-based learning to further make it easier for students to understand every concept or topic by correlating it with day-to-day experiences. In comparison to the other two subjects, the syllabus of JEE Advanced for physics is developed in such a way so as to test the deep understanding and application of concepts.

Q111. A lead bullet just melts when stopped by an obstacle. Assuming that 25% of heat is absorbed by the obstacle, find the minimum velocity of the bullet if its initial temperature is 27°C (melting point of lead = 327°C; specific heat of lead =0.03 cal/g°C; latent heat of fusion of lead = 6 cal/g and J=4.2 J/cal)

•  450 m/s
•  398 m/s
•  420 m/s
•  410 m/s

Solution

Q112. Two metal cubes A and B of same size are arranged as shown in the figure. The extreme ends of the combination are maintained at the indicated temperatures. The arrangement is thermally insulated. The coefficients of thermal conductivity of A and B are 300W/m℃ and 200W/m℃, respectively. After steady state is reached, the temperature of the interface will be

•  45℃
•  90℃
•  30℃
•  60℃

Solution

Q113. A brass wire 2 m long at 27℃ is held taut with negligible tension between two rigid supports. If the wire is cooled to a temperature of -33°C, then the tension developed in the wire, its diameter being 2 mm, will be (coefficient of linear expansion of brass =2.0×10^(-5)/°C and Young’s modulus of brass =0.91×10¹1Pa)

•   3400 N
•  34 kN
•  0.34 kN
•  6800 N

Solution

Q114. There rods of same dimensions are arranged as shown if Figure. They have thermal conductivities K_1,K_2 and K_3. The points P and Q are maintained at different temperatures for the heat to flow at the same rate along PQR and PQ. Which of the following options is correct?

•  K_3=1/2(K_1+K_2)
•  K_3=K_1+K_2
•  K_3=(K_1 K_2)/(K_1+K_2 )
•  K_3=2(K_1+K_2)

Solution

Q115. In an industrial process 10 kg of water per hour is to be heated from 20°C to 80°C. To do this steam at 150°C is passed from a boiler into a copper coil immersed in water. The steam condenses in the coil and is returned to the boiler as water at 90°C. How many kilograms of steam is required per hour (specific heat of steam=1 cal/g°C, Latent heat of vapourization = 540 cal/g)?

•  1 g
•  1 kg
•  10 g
•  10 kg

Solution
 

Q116. Liquid oxygen at 50 K is heated to 300 K at constant pressure of 1 atm. The rate of heating is constant. Which of the following graphs represents the variations of temperature with time?

•  
  
•  
  
• 
•  
  

Solution
116 (c) Temperature of liquid oxygen will first increase in the same phase. The phase change (liquid to gas) will take place. During which temperature will remain constant. After that temperature of oxygen in gaseous state will further increase.

Q117. A mass m of lead shot is placed at the bottem of a vertical cardboard cylinder that is 1.5 m long and closed at both ends. The cylinder is suddenly inverted so that the shot falls 1.5 m. If this process is repeated quickly 100 times, assuming no heat is dissipated or lost, the temperature of the shot will increase by (specific heat of lead = 0.03 cal/g°C)

•  0
•  5°C
•  7.3°C
•  11.3°C

Solution

Q118. A refrigerator is thermally equivalent to a box of cork board 90 mm thick and 6 m^2 in inner surface area, the thermal conductivity of cork being 0.05 W/mK. The motor of the refrigerator runs 15% of the time while the door is closed. The inside wall of the door, when it is closed, is kept, on an average, 22°C below the temperature of the outside wall. The rate at which heat is taken from the interior wall while the motor is running is

•  400 W
•  500 W
•  300 W
•  250 W

Solution

Q119. Consider two rods of same length and different specific heats (s_1 and s_2), conductivities K_1and K_2 and areas of cross section (A_1and A_2) and both having temperature T_1 and T_2 at their ends. If the rate of heat loss due to conduction is equal, then

•  K_1 A_1=K_2 A_2
•  K_2 A_1=K_1 A_2
•  (K_1 A_1)/s_1 =(K_2 A_2)/s_2
•  >(K_2 A_1)/s_2 =(K_1 A_2)/s_1

Solution

Q120. Figure shows the graphs of elongation versus temperature for two different metals. If these are employed to form a straight bimetallic strip of thickness 6 cm and heated, it bends in the form of an arc, the radius of curvature changing with temperature approximately as shown in the figure. The linear expansivities of the two metals are

•  24×10^(-6)/°C and 12×10^(-6)/°C
•  20×10^(-6)/°C and 10×10^(-6)/°C
•  18×10^(-6)/°C and 9×10^(-6)/°C
• 16×10^(-6)/°C and 8×10^(-6)/°C

Solution