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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
The unit of retardation is ____________
A body is moving vertically upwards. Its velocity changes at a constant rate from 50 m s−1 to 20 m s−1 in 3 s. What is its acceleration?
A bullet initially moving with a velocity 20 m/s strikes a target and comes to rest after penetrating a distance 10 cm into the target. Calculate the retardation caused by the target.
A space craft flying in a straight course with velocity of 75 km s-1 fires its rocket motors for 6.0 s. At the end of this time its speed is 120 km s-1 in the same direction.
Find
(i) The space craft's average acceleration while the motors were firing
(ii) The distance travelled by the space craft in the first 10 s after the rocket motors were started, the motors being in action for only 6 s.
If a body is moving with a constant velocity its acceleration is ______.
A ball is rolling from A to D on a flat and smooth surface. Its speed is 2 cm/s. On reaching B, it was pushed continuously up to C. On reaching D from C, its speed had become 4 cm/s. It took 2 seconds for it to go from B to C. What is the acceleration of the ball as it goes from B to C?
Give an example of an accelerated body, moving with a uniform speed.
From the diagram given below, calculate acceleration.
The speed of a car increases from 10 km/h to 64 km/h in 10 seconds. What will be its acceleration?
A body has an acceleration of -3.5 ms-2. What is its retardation?
A car accelerates uniformly from a velocity of 18 km/h to 36 km/h in 15 min. What is its acceleration?
Correct your friend who says that acceleration gives the idea of how fast the position changes.
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.
The acceleration of the body that moves with a uniform velocity will be ______.
A quantity has a value of 16ms-2. It is the ______.
A car is being driven at a speed of 20ms-1 when brakes are applied to bring it to rest in 5 s. The deceleration produced in this case will be ______.
Assertion: When a body is subjected to a uniform acceleration, it is always moving in a straight line.
Reason: Motion may be straight-line motion or circular motion.
