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A body of mass 2kg travels according to ...

A body of mass 2kg travels according to the law x(t) = `pt + qt^(2) + rt^(3)` where , q = `4 ms^(-2)` , p = `3 ms^(-1)` and `r = 5 ms^(-3)`. The force acting on the body at t = 2s is

A

136 N

B

134 N

C

158 N

D

68 N

Text Solution

Verified by Experts

The correct Answer is:
A
Given , mass = 2kg
`x(t) = pt + qt^(2) + rt^(3)`
v = `(dx)/(dt) = p + 2qt + 3rt^(3)`
`a = (dv)/(dt) = 0 + 2q + 6rt`
at t = 2s, a = 2q + 6 `xx 2 xx r`
= 2q + 12r
= `2 xx 4 + 12 xx 5`
= 8 + 60 = 68 m/s
Force = F = ma
`2 xx 68 = 136 N`
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Knowledge Check

  • A body of mass 2kg travels according to the law x (t) = pt + qt^(2) + rt^(3) where p = 3ms^(-1),q = 4 ms^(-2) and r = 5ms^(-3) .

    A
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    B
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    C
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    D
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