Centre of Mass & Rotational Motion · JEE Main previous year questions

2014 3 questions

1. Q312014 · 6 Apr 2014 · Shift 1

   A student measured the length of a rod and wrote it as 3.50 cm. Which instrument did he use to measure it?

   1. A.A screw gauge having 100 divisions in the circular scale and pitch as 1 mm.
   2. B.A screw gauge having 50 divisions in the circular scale and pitch as 1 mm.
   3. C.A meter scale.
   4. D.A vernier calliper where the 10 divisions in vernier scale matches with 9 divisions in main scale and main scale has 10 divisions in 1 cm.
   Show answer

   Answer: D

2. Q402014 · 6 Apr 2014 · Shift 1

   Three rods of Copper, Brass and Steel are welded together to form a $Y$ shaped structure. Area of cross - section of each rod $=4\mathrm{c}{\mathrm{m}}^2$. End of copper rod is maintained at $100^{\circ }\mathrm{C}$ where as ends of brass and steel are kept at $0^{\circ }\mathrm{C}$. Lengths of the copper, brass and steel rods are $46$, $13$ and $12\mathrm{cms}$ respectively. The rods are thermally insulated from surroundings excepts at ends. Thermal conductivities of copper, brass and steel are $0.92,0.26$ and $0.12\mathrm{CGS}$ units respectively. Rate of heat flow through copper rod is:

   1. A.$1.2cal/s$
   2. B.$2.4cal/s$
   3. C.$4.8cal/s$
   4. D.$6.0cal/s$
   Show answer

   Answer: C

3. Q502014 · 6 Apr 2014 · Shift 1
   
   1. A.$1.57\mathrm{W}$
   2. B.$2.97\mathrm{W}$
   3. C.$14.85\mathrm{W}$
   4. D.$29.7\mathrm{W}$
   Show answer

   Answer: B