Question

A biker starts a race and crosses the half line in 3 second with speed 54 km/h and
after that he increases his speed uniformally at a rate 7.5 m/s2 and completed the
race in 5 second
(A) Acceleration in the first half of the race is 5 m/s2
(B) He finished the race with speed 108 km/h
(C) Acceleration in the second half of the race is 12.5 m/s2
Choose the correct option.
.)only A
)BOTH (B)AND(C)
)BOTH (A)AND (B)
ALL (A),(B) AND (C)​

Answer 1

Answer:

b is the answer

Explanation:

Solution :

Speed=54km/h=54×1000/3600 =15ms-1

t=3s

S=15×3=45m

increases his speed uniformaly in the last 5s

u=15ms-1

a=7.5m/s2

t=2sec

v=u+at

v=15+7.5×2= 30ms-1

30×3600/1000 =108km/h