1.

A body moving with uniform acceleration travels 84 m in the first 6 s and 180 m in the next 5 s. Find : (a) the initial velocity, and (b) the acceleration of the body.

Answer»

Solution :Let u be the initial velocity and a be the ACCELERATION of the body.
Given, `S_(1), = 84` m, `t_(1), = 6` s,
`S_(2), = 84 + 180` = 264 m and `t_(2), = 6 + 5 = 11` s
From relation `S = UT +(1)/(2) at^(2)`
Distance travelled in 6 s.
`84 = u xx6+(1)/(2) a xx (6)^(2)`
or 6u +18 a = 84 or u +3a= 14
Distance travelled in 11 s .
`264 =u xx11+(1)/(2) a xx (11)^(2)`
or 11 u +`(121)/(2)a = 264` or u `+(11)/(2) a = 24`
On solving eqns. (i) and (ii) .
Initial velocity of body u = 2 `m s^(-1)`
and acceleration ` a =4 m s^(-2)`.


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