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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 `p = 3ms^(-1),q = 4 ms^(-2)` and `r = 5ms^(-3)` . Find the force acting on the body at t=2 sec.

A

136 N

B

134 N

C

158 N

D

68 N

Text Solution

Verified by Experts

The correct Answer is:
A
Given, mass `=2` kg
`x(t)=pt=pt+qt^(2)+rt^(3)`
`v=(dx)/(dt)=p+2qt+3rt^(2)`
`a=(dv)/(dt)=0+2q+6 rt`
At `t=2 s, a=2q+6xx2xxr=2q+12 r`
`=2xx4+12xx5=8+60=68 ms^(-1)`
Force, `F=ma=2 xx68=136 N`
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