Question

Q.28 a body starts from rest under uniform acceleration. If distance covered by it in 3rd second is 3 m, then distance covered in 5th second will be

Answer 1

Hallo dear ^ ^

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case 1 - - - - - - - - - - - - - - - - - - - - - - - -

u = 0

a = ?

s = 3 m

t = 3 sec

s = ut + 1/2 at^2

3 = 0×3 + 1/2 × a × ( 3 ) ^2

3 = 1/2 × 9 × a

3/9 × 2/1 = a

1/3 × 2/1 = a

therefore, a = 2/3 ms^-2

now ,

case 2 - - - - - - - - - - - - - - - - - - - - - - -

u = 0

a = 2/3 ms^-2 -------------[ From case 1 ]

t = 5 sec

s = ?

now ,

s = ut + 1/2at^2

s = 0×5 + 1/2 × 2/3 × (5)^2

s = 1/3 × 25

s = 8.3 m

hence , distance coverd in 5th sec is 8.3 m

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