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प्रश्न
Right or wrong sentence:
The value of gravitational acceleration at the centre of earth is zero.
विकल्प
Right
Wrong
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उत्तर
The given sentence is right.
Explanation:
Gravity is a vector. By symmetry (Newton’s shell theorem) the gravitational pull of all mass elements around the centre cancels at the centre, so the net gravitational acceleration there is zero. For a uniform spherical Earth, one finds `M(r) ∝ r^3 so g(r)`
= `G·M(r)/r^2 ∝ r`
Hence, g(0) = 0
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संबंधित प्रश्न
Gravitational force acts on all objects in proportion to their masses. Why then, a heavy object does not fall faster than a light object?
A stone is thrown vertically upward with an initial velocity of 40 m/s. Taking g = 10 m/s2, find the maximum height reached by the stone. What is the net displacement and the total distance covered by the stone?
A stone is allowed to fall from the top of a tower 100 m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25 m/s. Calculate when and where the two stones will meet.
Explain why, if a stone held in our hand is released, it falls towards the earth.
The values of g at six distances A, B, C, D, E and F from the surface of the earth are found to be 3.08 m/s2, 9.23 m/s2, 0.57 m/s2, 7.34 m/s2, 0.30 m/s2 and 1.49 m/s2, respectively.
(a) Arrange these values of g according to the increasing distances from the surface of the earth (keeping the value of g nearest to the surface of the earth first)
(b) If the value of distance F be 10000 km from the surface of the earth, state whether this distance is deep . inside the earth or high up in the sky. Give reason for your answer.
Explain why, a wide steel belt is provided over the wheels of an army tank.
An object thrown vertically upwards reaches a height of 500 m. What was its initial velocity? How long will the object take to come back to the earth? Assume g = 10 m/s2.
What will be the weight of a person on earth, who weighs 9N on the moon?
A metal ball of mass 5 kg falls from a height of 490 m. How much time it will take to reach the ground? (g = 9.8 m/s2)
What would be the value of ‘g’ on the surface of the earth if its mass was twice and its radius half of what it is now?
The total energy of an object falling freely towards the ground ______.
A body is projected vertically upward with an initial velocity u . If acceleartion due to gravity is g , the time for which it remains in air , is :
In vacuum, all freely falling objects have the same force. Is it true?
The free fall of an object is possible only in ______.
Write scientific reasons.
The value of gravitational acceleration (g) decreases as we go deep inside the earth.
Write scientific reasons.
When we drop a feather and a stone at the same time from a height the stone reach the earth faster than a feather.
Calculate the escape velocity on the surface of the moon given the mass and radius of the moon to be 7.34 × 1022 kg and 1.74 × 106 m respectively.
(Given: G = 6.67 × 10-11 Nm2/kg2)
When is free fall possible?
