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The distance s metres of a particle from a fixed point at ti...

The distance s metres of a particle from a fixed point at time t seconds is given by s=7+pt3+t2, where p is a constant. If the acceleration at t = 3 secs is 8ms2, find the value of p.

A.

13

B.

49

C.

59

D.

1

Correct answer is A

Differentiate distance twice to get the acceleration and then equate to get p.

s=7+pt3+t2

dsdt=v(t)=3pt2+2t

dvdt=a(t)=6pt+2

a(3)=6p(3)+2=818p=82=6

p=618=13