General
✓✗A light rod of length 2 m is suspended horizontally from the ceiling by two wires of equal length, one of steel (area 0.1 cm2) and one of brass (area 0.2 cm2), tied at its ends. A weight is hung from the rod. If the stresses in the two wires are to be equal, the weight must hang at a distance from the steel wire of
- 2/3 m
- 4/3 m
- 1/2 m
- 1 m
General
✓✗Small insects can walk on water. If soap is added to the water, they may sink because
- soap increases the surface tension
- soap increases the density of water
- soap reduces the surface tension
- soap increases the viscosity
General
✓✗The density of a substance at 0°C is \( \rho_0 \). Its coefficient of volume expansion is \( \gamma \). Its density at ΔT is approximately
- \( \rho_0(1 + \gamma\Delta T) \)
- \( \rho_0\gamma\Delta T \)
- \( \rho_0 \)
- \( \rho_0(1 - \gamma\Delta T) \)
General
✓✗A cylindrical rod having temperature T1 and T2 at its end. The rate of flow of heat Q1 cal/sec. If all the linear dimension are doubled keeping temperature constant, then rate of flow of heat Q2 will be
- Q1/4
- Q1/2
- 2Q1
- 4Q1
General
✓✗A metal rod is 1 m long at 0°C and 1.0012 m at 60°C. Its coefficient of linear expansion is
- 2 × 10−4 K−1
- 2 × 10−5 K−1
- 1.2 × 10−5 K−1
- 2 × 10−6 K−1
General
✓✗An aeroplane gets dynamic lift mainly because
- air flows slower over the top of the wing
- air flows faster over the top of the wing, so the pressure there is lower
- the wing is lighter than air
- air is denser above the wing
General
✓✗A fluid is in streamline flow across a horizontal pipe of variable area of cross section. For this which of the following statements is correct?
- The velocity is maximum at the narrowest part of the pipe and pressure is maximum at the widest part of the pipe.
- The velocity is minimum at the narrowest part of the pipe and the pressure is minimum at the widest part of the pipe.
- Velocity and pressure both are maximum at the widest part of the pipe.
- Velocity and pressure both are maximum at the narrowest part of the pipe.
General
✓✗Match List I with List II.
| List I | List II |
| P. Pascal's law | 1. Venturi-meter |
| Q. Bernoulli's principle | 2. Hydraulic brakes |
| R. Stokes' law | 3. Rise of oil in a lamp wick |
| S. Capillarity | 4. Terminal velocity of a falling raindrop |
- P-2, Q-1, R-3, S-4
- P-2, Q-1, R-4, S-3
- P-1, Q-2, R-4, S-3
- P-4, Q-1, R-2, S-3
General
✓✗A material that can be drawn into thin wires is called
- brittle
- plastic only within the elastic limit
- elastomer
- ductile
General
✓✗A block of wood floats in water with 3/5 of its volume submerged. Its density is
- 600 kg m−3
- 750 kg m−3
- 1600 kg m−3
- 400 kg m−3
General
✓✗Hooke's law states that, within the elastic limit,
- strain is independent of stress
- stress is inversely proportional to strain
- stress is proportional to the square of strain
- stress is proportional to strain
General
✓✗Two rods of equal length L and equal area, made of materials with Young's moduli Y1, Y2 and expansion coefficients α1, α2, are placed end to end between two rigid walls and heated through ΔT. The common compressive stress S in the rods satisfies
- \( S\left(\dfrac{1}{Y_1} + \dfrac{1}{Y_2}\right) = (\alpha_1 + \alpha_2)\Delta T \)
- \( S\left(\dfrac{1}{Y_1} + \dfrac{1}{Y_2}\right) = (\alpha_1 - \alpha_2)\Delta T \)
- \( S(Y_1 + Y_2) = (\alpha_1 + \alpha_2)\Delta T \)
- \( S = (Y_1\alpha_1 + Y_2\alpha_2)\Delta T \)
General
✓✗If \( \lambda_m \) denotes the wavelength at which the radiative emission from a black body at a temperature T K is maximum, then
- \( \lambda_m \) is independent of T
- \( \lambda_m \) ∝ T−1
- \( \lambda_m \) ∝ T
- \( \lambda_m \) ∝ T4
General
✓✗A load hung from a wire of length L produces an extension l. The wire is cut into three equal pieces, which are placed side by side (in parallel) to support the same load. The extension now is
- l/9
- l/3
- 3l
- l
General
✓✗Two rods of the same length and area, with conductivities 2K and K, are joined in series. Their outer ends are at 90°C (rod 2K side) and 0°C. The junction temperature is
- 67.5°C
- 45°C
- 60°C
- 30°C