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)
a_t = 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

a_n = v²/r = 100²/234.67 =42.6 m/s²


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