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प्रश्न
Give a scientific reason.
When an object falls freely to the ground, its acceleration is uniform.
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उत्तर
When an object falls freely to the ground, it is under the effect of a constant force known as the force of gravity. No other forces act on it. Hence, from Newton's second law of motion, we can say that this constant force of gravity accelerates the freely falling object uniformly. This uniform acceleration is known as acceleration due to gravity which acts towards the centre and is denoted by g.
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संबंधित प्रश्न
Give one example of the following motion:
Uniform retardation
Figure shows the velocity-time graphs for two cars A and B moving in the same direction. Which car has greater acceleration? Give reasons to your answer.
A body falls freely from a certain height. Show graphically the relation between the distance fallen and square of time. How will you determine g from this graph?
Figure given below shows a velocity-time graph for a car starting from rest. The graph has three parts AB, BC and CD.
(a) Is the magnitude of acceleration higher or lower than that of retardation ? Give a reason .
(b) Compare the magnitude of acceleration and retardation .
When is the acceleration due to gravity positive?
When is the acceleration due to gravity negative?
A racing car is moving with a velocity of 50 m/s. On
applying brakes, it is uniformly retarded and comes to rest in 20 seconds. Calculate its acceleration.
Diagram is given below shows velocity – time graph of car P and Q, starting from the same place and in the same direction. Calculate the Acceleration of car P.
A motorbike, initially at rest, picks up a velocity of 72 kmh−1 over a distance of 40 m. Calculate
- acceleration
- time in which it picks up above velocity.
State if the following situation is possible:
A body moving with constant acceleration but with Zero velocity.
State if the following situation is possible:
A body moving with a constant velocity in an accelerated motion.
A car accelerates uniformly from a velocity of 18 km/h to 36 km/h in 15 min. What is its acceleration?
The graph shows how the velocity of a scooter varies with time in 50 s.
Work out: Acceleration.
A bus can accelerate with an acceleration of 1 m/s2 . Find the minimum time for the bus to attain the speed of 100 km/s from 50 km /s.
State whether true or false. If false, correct the statement.
Acceleration can get negative value also.
Exercise Problem.
A racing car has a uniform acceleration of 4 ms–2. What distance it covers in 10 s after the start?
Acceleration is defined as the rate of change of ______.
If a body starts from rest, what can be said about the acceleration of the body?
Assertion: A positive acceleration of a body can be associated with the slowing down of the body.
Reason: Acceleration is a vector.
What is the difference between uniform acceleration and non–uniform acceleration?
