Parallel rays of light of intensity $$I$$ = 912 Wm^–2 are incident on a spherical black body kept in surroundings of temperature 300 K. Take Stefan-Boltzmann constant $$\sigma $$ = 5.7 $$ \times $$ 10^–8 Wm^–2K^–4 and assume that the energy exchange with the surroundings is only through radiation. The final steady state temperature of the black body is close to

A person in a lift is holding a water jar, which has a small hole at the lower end of its side. When the lift is at rest, the water jet coming out of the hole hits the floor of the lift at a distance d of 1.2 m from the person. In the following, state of the lift’s motion is given in List I and the distance where the water jet hits the floor of the lift is given in List II. Match the statements from List I with those in List II and select the correct answer using the options given below the lists.

List - I	List - II
P. Lift is accelerating vertically up.	1. d=1.2 m
Q. Lift is accelerating vertically down with an acceleration less than the gravitational acceleration.	2. d > 1.02 m
R. Lift is moving vertically up with constant speed.	3. d < 1.2 m
S. Lift is falling freely.	4. No water leaks out of the jar

A planet of radius R = $${1 \over {10}} \times $$ (radius of Earth) has the same mass density as Earth. Scientists dig a well of depth $${R \over 5}$$ on it and lower a wire of the same length and of linear mass density 10^-3 kg m^-1 into it. If the wire is not touching anywhere, the force applied at the top of the wire by a person holding it in place is (take the radius of Earth = 6 $$ \times $$ 10⁶ m and the acceleration due to gravity of Earth is 10 ms ^-2)

A tennis ball is dropped on a horizontal smooth surface. It bounces back to its original position after hitting the surface. The force on the ball during the collision is proportional to the length of compression of the ball. Which one of the following sketches describes the variation of its kinetic energy K with time t most appropriately? The figures are only illustrative and not to the scale.