Question

A body travels 200 cm in the first 2 s and 220 cm in the next 4s with deceleration. The velocity of the body at the end of the 7th second is

Answer 1

Answer:

10 cm/s

Explanation:

200 = u 2  - (1/2)a(2)²

=> u - a = 100

420 = u(2 + 4) - (1/2)(2 + 4)² a

or u - 3 a = 70

Solving equations (i) and (ii), we get

a = 15 cm/s² and u = 115 cm/s.

at  =15 * 7

v = u - at =115 -105 =10 cm/s .

Answer 2

Answer:200 = u × 2 -(1/2)a(2)^2

= u - a = 100

200 + 220 = u(2 + 4) - (1/2)(2 + 4)^2 a

or u - 3 a = 70

Solving equations (i) and (ii), we get a = 15 cm/s ^2 and u = 115 cm/s.

Further, v = u - at =115 -15 * 7 =10 cm/s .

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