Let original radius = r

Original temperature = T

Original power radiated = P

According to Stefan-Boltzmann Law, Power radiated by black body = {tex}P = σAT^4=\sigma 4\pi r^2T^4{/tex}

{tex}=> 500 = 4\sigma \pi r^2T^4{/tex}

New radius = {tex}r\over 2{/tex}

New temperature = 2T

New power P` = {tex}4\sigma \pi \times {r^2\over 4}\times 16T^4{/tex}

{tex}4\times (4\sigma \pi r^2T^4)= 4\times P{/tex}{tex}= 4\times 450= 1800{/tex}

Power becomes 1800 W

A constant current is a type of Direct Current (DC) that does not change its intensity with time.

As from the equation of motions for free fall we have

v²-u²=-2gh     ( at peak point v = 0)

therefore,   -u² = -2hg

                  h = u²/2g

As from the above equation h is inversely proportional to g and g on mountains is less from the surface

hence tennis ball bounces more on the mountains than on the plains.