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प्रश्न
Define acceleration due to gravity.
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उत्तर
The acceleration produced in a body under the influence of the force of gravity alone is called acceleration due to gravity.
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संबंधित प्रश्न
A ball is thrown vertically upwards with a velocity of 49 m/s. Calculate
- the maximum height to which it rises.
- the total time it takes to return to the surface of the earth.
A stone is released from the top of a tower of height 19.6 m. Calculate its final velocity just before touching the ground.
Explain what is meant by the equation :
`g= Gxxm/r^2`
where the symbols have their usual meanings.
Give reason for the following :
The force of gravitation between two cricket balls is extremely small but that between a cricket ball and the earth is extremely large.
Name the force which wears away two surfaces as they move over one another.
Name the force which pulled the apple off Isaac Newton’s tree.
Name the force which stops you falling through the floor.
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)
The acceleration produced in a body by a force of given magnitude depends on
A force acts for 0.1 s on a body of mass 2.0 kg initially at rest. The force is then withdrawn and the body moves with a velocity of 2 m s-1. Find the magnitude of the force.
A car is moving with a uniform velocity 30 ms-1. It is stopped in 2 s by applying a force of 1500 N through its brakes. Calculate the following values : The retardation produced in car.
A body falls freely under gravity from rest and reaches the ground in time t. Write the expression for the height fallen by the body.
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 :
What force, in newton, your muscles need to apply to hold a mass of 5 kg in your hand? State the assumption.
Explain why:
Objects fall to the earth.
What do you understand by the free fall?
The free fall of an object is possible only in _______.
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.
1) 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.
2) Why does free fall not happen on the earth?
3) Why does the velocity of the object increase during the free fall?
4) Which type of force exerts on the object during free fall?
5) Why does free fall happen only in a vacuum?
