A car is travelling along a curved path of radius
200 ft. If its initial speed is 10 ft/s and if the speed is increasing at (1.2)t ft/s2, what is the magnitude of its acceleration when t = 5 s.

a. 6.56 ft/s2
b. 6.66 ft/s2
c. 6.86 ft/s2
d. 6.76 ft/s2

Given data:

r   - radius of curved path = 200 ft
v0 - Initial speed = 10 ft/s

When t = 5 s
v = (0.6) 25 + 10 = 15 + 10 = 25 ft/s

an = v2/r = 252/200 = 3.125 ft/s2
at = (1.2) 5 = 6 ft/s2


The acceleration of the car when t = 5 s is 6.76 ft/s2.