General
✓✗During melting of ice at 0°C, its temperature
- decreases
- remains constant
- increases
- first increases then decreases
General
✓✗Water is heated from 0°C to 10°C. Its volume
- remains constant
- first decreases up to 4°C and then increases
- decreases steadily
- increases steadily
General
✓✗Two wires A and B of the same material are joined end to end and loaded with a weight W. A has length L and diameter d; B has length 2L and diameter 2d. The ratio of the strains in A and B is
- 1 : 4
- 1 : 1
- 4 : 1
- 2 : 1
General
✓✗A uniform rod is held vertically and a mass M is hung from its lower end. Neglecting the weight of the rod, the stress at the midpoint of the rod compared with that at its upper end is
- zero
- double
- the same
- half
General
✓✗Within the elastic limit, the extension of a wire (all other things the same) is directly proportional to
- the applied load
- the square of its diameter
- the square of the load
- its Young's modulus
General
✓✗The ideal gas equation for n moles is
- PV = nR/T
- P = nRTV
- PV = RT/n
- PV = nRT
General
✓✗Detergents are effective in removing grease from clothes mainly because they
- increase the viscosity of water
- increase the density of water
- reduce the surface tension of water
- increase the surface tension of water
General
✓✗A U-tube contains mercury. Water is poured into one arm until the water column is 13.6 cm high. The difference between the mercury levels in the two arms is (density of mercury 13.6 g cm−3)
- 1 cm
- 2 cm
- 13.6 cm
- 0.5 cm
General
✓✗The steel cables of cranes are made of many thin wires braided together rather than one solid wire mainly because
- it reduces the weight to zero
- braiding increases the density of steel
- thin wires have a larger Young's modulus
- this gives flexibility with the same strength
General
✓✗The height of a water barometer at normal atmospheric pressure would be about
- 1 m
- 10.3 m
- 76 cm
- 100 m
General
✓✗A pendulum clock with a brass rod (α = 2 × 10−5 K−1) keeps correct time at 20°C. At 30°C it loses about
- 8.64 s per day
- 86.4 s per day
- 4.32 s per day
- 17.3 s per day
General
✓✗If a soap bubble expands, the pressure inside the bubble
- is equal to the atmospheric pressure
- decreases
- increases
- remains the same
General
✓✗Two wires A and B of equal length and area, with YA = 2YB, are hung side by side from a rigid support and together support a load W through a light horizontal bar that stays horizontal. The forces in A and B are then
- in the ratio 1 : 2
- in the ratio 2 : 1
- equal
- in the ratio 4 : 1
General
✓✗A wire of mass m, length L, area A and Young's modulus Y hangs vertically with a block of mass M at its lower end. The total extension of the wire is
- \( \dfrac{(M + m)gL}{AY} \)
- \( \dfrac{(M + m/2)gL}{AY} \)
- \( \dfrac{(M + 2m)gL}{2AY} \)
- \( \dfrac{MgL}{AY} \)
General
✓✗Water is used as a coolant in car radiators mainly because it has
- a low boiling point
- a high density
- a high specific heat capacity
- a low specific heat capacity