Question

prove it that answer is 54km/hr​

Answer 1

Answer:

option (3) 30 kmph

Explanation:

greatest speed is achieved when the car will be at the end of its acceleration time, and moves with constant speed, v = 60kmph.

let the respective time slots for each period be t:8t:t

let acceleration be a

thus if initial velocity = 0

then using first equation of motion:

v = 60 = a.t ______eq(1)

distance travelled while this time: s1 = 1/2 a.t2 = 1/2 60t = 30t (from eq(1) )

distance traveled in next constant sped slot:

s2 = 60x8t = 240t (using ratio here t= 8t)

let retarding be at rate r

thus using first eq of motion:

60 = rt

distance travelled in this slot:

s3 = (60)2/2r = 30t

thus average speed = total distance / total time = (30t+240t+30t)/10t = 30 kmph

plz mar brainliest plzzz.