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Solve these numericals:-            (PLEASE HELP, URGENTLY NEEDED!) 1) A stone is dropped from a tall building of 80 metres height. Find its final velocity and the time taken to touch the ground (take g = 10 metres per second square). 2) A car initially at rest starts moving with an acceleration of 0.5 metres per second square and travels a distance of 25 metres. Calculate its final velocity and its time.

Answer»

s = 80 m = displacement       u = 0  = initial velocity           g = 10 m/sec/sec  acceleration of the STONE          equation of motion :  v² = u ² + 2 a s         v² = 0 + 2  * 10 * 80 = 1600        v = final velocity = 40 m/sec2)    u = 0        a = 0.50 m/sec/sec       s = 25 m         v² = u² + 2 a s             = 0 + 2 * 0.4 * 25  = 20           v = √20 m /sec = 2 √5 m/s         v = u + a t           t = (v - u) / a = 2√5 / 0.50  = 4 √5  seconds.



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