Black Body Radiation

If the temperature of black body is increased by a factor of 2, the amount of energy and volume radiated increases by a factor of . . . . . . . . . .

( a ) 2               ( b ) 4               ( c ) 8               ( d ) 16

Acceleration due to Gravity; The ratio of escape velocity.

The acceleration due to gravity ( g ) on the surface of the Earth is approximately 2 . 6 times that on the surface of the Mars . Given that the radius of Mars is about one half the radius of the Earth , the ratio of the escape velocity on Earth to that on Mars is approximately . . . . . . . . . . .

a ) 1 . 1
b ) 1 . 3
c ) 2 . 3
d ) 5 . 2 

The angle between vector ( i + j ) and ( j + k ) is ( in Radian )

The angle between vector ( i + j ) and ( j + k ) is ( in Radian )

solution :  -

Let us consider

A = i + j

B = j + k

To find out the