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HELP ASAP LAST QUESTION I PROMISE

HELP ASAP LAST QUESTION I PROMISE-example-1
User Joe Elleson
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1 Answer

11 votes
11 votes

Answer:


a=36\: \sf ms^(-2)

Explanation:


\textsf{Displacement}\:x=4t^3-27t+8


\implies \textsf{Velocity}\:v=(dx)/(dt)=12t^2-27


\implies \textsf{Acceleration}\:a=(dv)/(dt)=24t

At the moment the direction of motion of P reverses, the velocity of P will be zero. Therefore, find the value of t when v = 0:


\implies v=0


\implies 12t^2-27=0


\implies t^2=(27)/(12)=\frac94


\implies t=\pm√(\frac94)=\pm\frac32

As time is positive, P reverses when t = 3/2 s

To find acceleration at this time, simply substitute the found value of t into the equation for acceleration:


\implies a=24(\frac32)


\implies a=36\: \sf ms^(-2)

User Dietpixel
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