When two springs A and B with force constants kA and kB are stretched by the same force, then the respective ratio of the work done on them is
kB : kA
kA : kB
kA : kB : 1
Two capillary tubes A and B of diameter 1 mm and 2 mm respectively are dipped vertically in a liquid. If the capillary rise in A is 6 cm, then the capillary rise in B is
2 cm
3 cm
4 cm
6 cm
Two wires A and B of same material and of equal length with the radii in the ratio 1 : 2 are subjected to identical loads. If the lengthof A increases by 8 mm, then the increase in length of B is
2 mm
4 mm
8 mm
16 mm
After terminal velocity is reached, the acceleration of a body falling through a fluid is
equal to g
zero
less than g
greater than g
A liquid is filled upto a height of 20 min a cylindrical vessel. The speed of liquid coming out of a small hole at the bottom of the vessel is (take, g = 10ms-2)
1.2 ms-1
1 ms-1
2 ms-1
3.2 ms-1
A metallic bar of coefficient of linear expansion 10-5 K-1 is heated from 0°C to 100°C. The percentage increase in its length is
0.1 %
1 %
10 %
0.01 %
Two perfectly black spheres A and B having radii 8 cm and 2 cm are maintained at temperatures 127°C and 527°C, respectively. The ratio of the energy radiated by A to that by B is
1 : 2
1 : 1
2 : 1
1 : 4
B.
1 : 1
Total energy emitted per second by a unit area of a body is proportional to the fourth power of its absolute temperature.
i.e, E = σT4
where, σ is a universal constant called Stefan Boltzmann constant.
Given, T1 = 127°C
= 127 + 273 = 400 K
T2 = 527°C = 800 K
and r1 = 8 cm ⇒ r2 = 2 cm
We know that total energy,
E = σ AT4
In the first condition,
E1 = σ1 A1 T14 ......... (i)
In the second condition,
E2 = σ2 A2 T24 ......... (ii)
On dividing Eq. (i) by Eq. (ii), we get
For a monoatomic gas, the molar specific heat at constant pressure divided by the molar gas constant R is equal to
2.5
1.5
5.0
3.5
Hot water in a vessel kept in a room cools from 70°C to 65°C in t1 minutes, from 65°C to 60°C in t2 minutes and from 60°C to 55°C in t3 minutes then,
t1 < t2 > t3
t1 = t2 = t3
t1 < t2 < t3
t1 < t2 = t3