The jet plane has a speed of 100 m/s which is decreasing at a rate of 50 m/s2 when it reaches A. Evaluate the magnitude of its acceleration at this point.

a. 63.3 m/s2
b. 64.6 m/s2
c. 66.5 m/s2
d. 65.7 m/s2

Given data:
y  = 25 ln(x/70)
at = 50 m/s2
v  = 100 m/s


dy/dx = 25/x
d2y/dx2 = -25/x2

When x = 70 m
dy/dx = 25/70
d2y/dx2 = -25/702

Substituting the above values in the expression for r, we have
r = 234.67 m

an = v2/r = 1002/234.67 =42.6 m/s2


The accleration of the jet at A is 65.7 m/s2