The escape speed of a projectile on the earth’s surface is 11.2 km s–1. A body is
projected out with thrice this speed. What is the speed of the body far away from
the earth? Ignore the presence of the sun and other planets.
A rocket is fired vertically with a speed of 5 km s-1 from the earth’s surface. How far
from the earth does the rocket go before returning to the earth ? Mass of the earth
= 6.0 × 1024 kg; mean radius of the earth = 6.4 × 106
m; G = 6.67 × 10–11 N m2 kg–2
Assuming the earth to be a sphere of uniform mass density, how much would a
body weigh half way down to the centre of the earth if it weighed 250 N on the
surface ?
A body weighs 63 N on the surface of the earth. What is the gravitational force on it
due to the earth at a height equal to half the radius of the earth ?
A saturn year is 29.5 times the earth year. How far is the saturn from the sun if the
earth is 1.50 × 108
km away from the sun ?
How will you ‘weigh the sun’, that is estimate its mass? The mean orbital radius of
the earth around the sun is 1.5 × 108
km.
A rocket is fired from the earth towards the sun. At what distance from the earth’s
centre is the gravitational force on the rocket zero ? Mass of the sun = 2×1030 kg,
mass of the earth = 6×1024 kg. Neglect the effect of other planets etc. (orbital radius
= 1.5 × 1011 m)
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