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प्रश्न
What is escape velocity?
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उत्तर
The minimum velocity required to project an object to escape from the Earth's gravitational pull is known as escape velocity. It is given as: vesc = `sqrt((2"GM")/"R")`
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संबंधित प्रश्न
What do you mean by free fall?
What force is responsible for the earth revolving round the sun ?
State whether the following statement is true or false :
A falling stone also attracts the earth.
Fill in the following blank with suitable word :
The acceleration due to gravity on the moon is about ………………of that on the earth.
Explain what is meant by the equation :
`g= Gxxm/r^2`
where the symbols have their usual meanings.
What do you mean by the term free fall ?
Explain why, if a stone held in our hand is released, it falls towards the earth.
What is the force of gravity on a body of mass 150 kg lying on the surface of the earth? (Mass of earth = 6 x 1024 kg; Radius of earth = 6.4 x 106 m; G = 6.7 x 10-11 Nm2/kg2)
What is the usual value of the acceleration due to gravity of 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.
What will be the weight of a person on earth, who weighs 9N on the moon?
i) If g = GM/r2 then where will the value of g be high at Goa Beach or on top of Mount Everest?
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)
Choose one or more correct alternatives.
Which of the forces involved in dragging a heavy object on a smooth, horizontal surface, have the same magnitude?
- The horizontal applied force
- gravitational force
- reaction force in vertical direction
- force of friction
A force of 10 N acts on a body of mass 5 kg. Find the acceleration produced.
Right or wrong sentence:
The value of gravitational acceleration at the centre of earth is zero.
Read the given passage carefully and answer the questions.
| We know that the force of gravity due to the earth acts on each and every object. When we were holding the stone in our hand, the stone was experiencing this force, but it was balanced by a force that we were applying on it in the opposite direction. As a result, the stone remained at rest. Once we release the stone from our hands, the only force that acts on it is the gravitational force of the earth and the stone falls down under its influence. Whenever an object moves under the influence of the force of gravity alone, it is said to be falling freely. Thus the released stone is in a free fall. In free fall, the initial velocity of the object is zero and goes on increasing due to the acceleration due to the gravity of the earth. During free fall, the frictional force due to air opposes the motion of the object and a buoyant force also acts on the object. Thus, true free fall is possible only in a vacuum. |
- Complete the following statement by choosing the right option.
The stone held in the hand is stable because on it ......- two unbalanced forces are exerted.
- only the gravitational force of the earth is exerted.
- gravitational force of the earth is not exerted.
- two balanced forces are exerted.
- Why does free fall not happen on the earth?
- Why does the velocity of the object increase during the free fall?
- Which type of force exerts on the object during free fall?
- Why does free fall happen only in a vacuum?
When is free fall possible?
