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प्रश्न
Write scientific reason.
The value of gravitational acceleration (g) is taken to be -g when studying the motion of an object thrown upwards in a straight line.
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उत्तर
- For motion of an object thrown upwards, magnitude of g is the same throughout the motion but the velocity of the object decreases with the increase in height.
- For object thrown upwards, the direction of acceleration due to gravity is opposite to the velocity of the object.
- Hence, the value of gravitational acceleration (g) is taken to be -g when studying the motion of an object thrown upwards in a straight line.
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संबंधित प्रश्न
What do you mean by free fall?
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?
When an object is dropped from a height, it accelerates and falls down. Name the force which accelerates the object.
What do you mean by the term free fall ?
During a free fall, will heavier objects accelerate more than lighter ones ?
Explain why, a wide steel belt is provided over the wheels of an army tank.
A force of 15 N acts on a body of mass 2 kg. Calculate the acceleration produced.
A force of 10 N acts on a body of mass 5 kg. Find the acceleration produced.
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 The force is then withdrawn and the body moves with a velocity of 2 m s-1.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.
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In vacuum, all freely falling objects have the same force. Is it true?
The value of gravitational acceleration (g) is ________.
Free fall of an object does not depend on the mass of the object.
Write scientific reason.
The value of gravitational acceleration (g) decreases as we go deep inside the earth.
The mass of planet ‘X” is four times that of the earth and its radius is double the radius of the earth. The escape velocity of a body from the earth is 11.2 × 103 m/s. Find the escape velocity of a body from the planet 'X’.
Write a short note.
Escape Velocity
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?
