Question 16: A body is projected vertically from the earth's surface with velocity equal to half of the escape velocity. Maximum height reached by the body is:
Answer: (b)
Explantion: From conservation of mechanical energy
or,
Question 17: If the radius of the earth reduces by 4%, density remaining the same, then the escape velocity will:
Answer: (c) decrease by 4%
Question 18: The time period of artificial satelite in a circular orbit of radius R is T. The radius of the orbit in which time period is 8T is:
Answer: (c) 4 R
Explantion:
and
or
or R' = 4R
Question 19: A satellite is orbiting very colse to planet. Its time period depends only upon:
Answer: (a) density of the planet
Question 20: A body is projected with escape velocity 11.2 km/s from earth's surface. If the body is projected in a direction 30º angle to the vertical, its esacpe velocity in this case will be:
Answer: (a) 11.2 km/s
Explantion: Escape velocity does not depend on angle of projection, so it will remain same i.e., 11.2 km/s.
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