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CBSE Class 9 Answered

(a)state the unit of force and define it. (b)a stone is dropped from the edge of a 4.9m high roof. find out the following: (1)time taken to fall 4.9m (2)velocity just before it reaches the ground. (3)what is its acceleration after 1s and 2s. please its urgent!!
Asked by sahil ahmed | 24 Sep, 2013, 07:49: PM
answered-by-expert Expert Answer
(a) The unit of force is newton denoted as N.
It is defined as, "One newton is the force needed to accelerate a body of mass 1 kg at a rate of 1 metre per second squared".
 
(b) u = 0, h = 4.9 m, g = 9.8 m/s2.
 
1) The time taken to fall 4.9 m is:
 
2) The velocity just before it reaches the ground is:
 
3) The body is acted upon by the acceleration due to gravity which is constant throughout the motion. Thus, the acceleration of the stone after 1s and 2 s is 9.8 m/s2.
Answered by Romal Bhansali | 25 Sep, 2013, 09:56: AM

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