( iii ) Law of period The square of the time period of revolution of planet around the sun is directly proportional to the cube semi-major axis of its elliptical orbit .
T 2 & infi ; a 3 or ( T1 / T2 ) 2 = ( a1 / a2 ) 3 where , a = semi-major axis of the elliptical orbit .
Important Points
( i ) A missile is launched with a velocity less than the escape velocity . The sum of its kinetic energy and potential energy is negative .
( ii ) The orbital speed of jupiter is less than the orbital speed of earth .
( iii ) A bomb explodes on the moon . You cannot hear the sound of the explosion on earth .
( iv ) A bottle filled with water at 30 ° C and fitted with a cork is taken to the moon . If the cork is opened at the surface of the moon then water will boil .
( v ) For a satellite orbiting near earth ’ s surface ( a ) Orbital velocity = 8 km / s ( b ) Time period = 84 min approximately
( c ) Angular speed ω = 2π / 84 rad / min = 0.00125 rad / s
( vi ) Inertial mass and gravitational mass ( a ) Inertial mass = force / acceleration ( b ) Gravitational mass = weight of body / acceleration due to gravity ( c ) They are equal to each other in magnitude .
( d ) Gravitational mass of a body is affected by the presence of other bodies near it . Inertial mass of a body remains unaffected by the presence of other bodies near it .