Question

49. A body starts with some initial velocity along as
line. After 3 s it is found to be at a distance of 15 m
the starting point. At 4 s it is at starting point. What
initial velocity of the body? (Assume constant acceleration)

(a) 20 m/s
(b) 10 m/s
(d) 15 m/s


(c) 5 m/s
​

Answer 1

Answer:

a) 20m/s

Explanation:

u=0, t=3sec, s=15m, a=a

s= ut+1/2 at²

a= 15×2/9= 5×2/3

Case 2

t2= 4sec

S=u2t2+1/2at2²

15=u2 × 4+ 1/2×(5×2/3)×16= 4u2 + 5×2×8/3

u= (15-80/3)/4