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An automobile of mass m accelerates, sta...

An automobile of mass m accelerates, starting from rest, while the engine supplies constant power P, its position and instantaneous velocity changes w.r.t. time assuming the automobile starts from rest.

Text Solution

Verified by Experts

Velocity: As `Fv=P=cont ant`, i.e.,
`m(dv)/(dt)v=P[as F=(mdv)/(dt)]`
or `int vdv=int (P)/(m)dt`
By integrating both sides , we get `v^2/2=P/mt+C_1`
As initially the body is at rest, i.e. `v=0` at `t=0`, so `C_1=0`
`:.v=((2Pt)/(m))^(1//2)`
Position: From the above expression, `v=((2Pt)/(m))^(1//2)`
or `(ds)/(dt)=((2Pt)/(m))^(1//2)` [ As `v=(ds)/(dt)`]
i.e., `intds=int((2Pt)/(m))^(1//2)dt`
By integrating both sides, we get
`s=((2P)/(m))^(1//2)*(2/3)t^(3//2)+C_2`
Now as at `t=0`, `s=0`, so `C_2=0`.
`s=((8P)/(9m))^(1//2)t^(3//2)`
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Knowledge Check

  • An automobile of mass 'm' accelerates starting from origin and initially at rest, while the engine supplies constant power P. The position is given as a function of time by :

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  • An automobile engine of mass m accelerates and a constant power P is applied by the engine. The instantaneous speed of the engine will be

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