Which of the following represents convection ?

Solution
All the given phenomena are caused due to convection.
The rate of flow of heat through a rod depends on:

Solution
Rate of flow of heat through arod,
\(H=\frac{KA}{2}\Delta T\)
A and B are two wires. The radius of A is twice that of B. They are stretched by the same load. Then the stress on B is

Solution
\(stress=\frac{force}{Area}\)∴\(stress\alpha \frac{1}{\pi r^{2}}\)
\(\frac{S_{B}}{S_{A}}=\left ( \frac{r_{A}}{r_{B}} \right )^{2}=(2)^{2}\)⇒S_{B}=4S_{A}
Hydraulic lift is based on the principle of

Solution
Hydraulic lift is based on the principle of Pascal’s law.
A hole is drilled through the earth along the diameter and a stone is dropped into it. When the stone is at the centre of earth, it possesses

Solution
At the centre of earth, weight is zero as g=0 at center of earth.
weight=mg=0 and Potential energy=mgh But mass≠0 as mass is the quantity of matter.
A person sitting on a chair in a satellite feels weightless because

Solution
The weightlessness inside a satellite is due to the fact that the surface does not exert any force on the body and hence its apparent weight is zero.

Solution
From Kepler's 2^{nd} law –The straight line joining thesun and the planet sweeps out equal areas in equaltime intervals (\(\frac{dA}{dt}\)= const;area swept) Areal velocity of the satellite is given by \(\frac{dA}{dt}\)=^{1}⁄_{2}ωr^{2}=const.=\(\frac{L}{2m}\) where ω= angular velocity of the satellite L =mvr= mωr^{2}=const, showing that Kepler's 2^{nd} law is a consequence of the conservation of angular momentum.

Solution
\(V_{0}=\sqrt{\frac{GM}{r}}\)i.e., v_{0}independent of mass of the satellite.
If suddenly the gravitational force of attraction between the earth and a satellite revolving around it becomes zero, then the satellite will

Solution
Due to inertia of motion it will move tangentially to the original orbit with same velocity.

Solution
Since orbital velocity of satellite is\(V_{0}=\sqrt{\frac{GM}{r}}\), it does not depend upon the mass of the satellite.Therefore, both satellites will move with same speed.