Class 10 Science and Technology Part 1 – Chapter 1: Gravitation MCQ
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According to Kepler's third law, the square of a planet's period of revolution is directly proportional to which quantity?
Chapter 1: Gravitation
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Answer: C. The cube of its mean distance from the Sun
Kepler's third law: T² ∝ r³, i.e. T²/r³ is a constant.The distance between two objects is made three times, their masses staying the same. The gravitational force between them becomes:
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Answer: B. One-ninth
F ∝ 1/d², so tripling d makes the force 1/3² = 1/9 of its earlier value.What is the SI unit of the universal gravitational constant G?
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Answer: A. N m² kg⁻²
From F = G m₁m₂/d², G = F d²/(m₁m₂), so its unit is N m²/kg².On the Earth's surface, where is the value of g the highest?
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Answer: B. At the poles
The Earth is flatter at the poles, so the radius is smallest there and g is highest (about 9.832 m/s²).An object has a mass of 60 kg. Taking g = 9.8 m/s², what is its weight on the Earth?
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Answer: D. 588 N
Weight W = m g = 60 × 9.8 = 588 N; mass stays 60 kg, weight is a force in newtons.What is the escape velocity on the surface of the Earth?
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Answer: C. 11.2 km/s
v(esc) = √(2gR) = √(2 × 9.8 × 6.4 × 10⁶) ≈ 11.2 km/s (2.37 km/s is the Moon's value).A stone is dropped from rest and falls freely. Taking g = 10 m/s², how far does it fall in the first 3 seconds?
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Answer: A. 45 m
For free fall s = ½ g t² = ½ × 10 × 3² = 45 m (30 m/s is its velocity at 3 s).Why do astronauts and objects inside an orbiting spacecraft appear weightless?
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Answer: B. They are in a state of free fall
g there is only about 11% less than on the surface; they float because the craft and everything in it are in free fall.With the same effort, a boy jumps 0.5 m high on the Earth. About how high could he jump on the Moon?
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Answer: C. 3 m
g on the Moon is about 1/6 of the Earth's, so the same force lifts him about 6 times higher: 6 × 0.5 = 3 m.A stone tied to a string is whirled in a circle. If the string is released, how does the stone move?
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Answer: D. It moves along the tangent to the circle at that point
Once the centripetal force (the pull of the string) stops, the stone flies off along the direction of its velocity, the tangent.
All questions are written by PadhaiNotes in our own words from this chapter of the official Maharashtra State Board Balbharati textbook.