Question

A car accelerated uniformaly from 18 km/hr to 36km/hr in 5 sec . calculate (i) the acceleration (ii)distance cvered by the car in that time.

Answer 1

18km/hr = 18x1000/60x60 m/s = u(initial)
36km/hr = 36x1000/60x60 m/s = v(final)
time (t) = 5s

v = u+at
36x1000)/(60x60) = (18x1000)/(60x60) + a(5)
36000/3600 = 18000/3600 + 5a
(36000-18000)/3600 = 5a
18000/3600 = 5a
180/36 = 5a
5 = 5a
a = 1m/s²

s = ut + ½at²
s = 5(5) + ½(1)(5)²
s = 25 + ½(25)
s = 25(1+½)
s = 25(3/2)
s = 75/2
s = 37.5m

SO,
(i) a=1m/s²
(ii) s=37.5m


I know it's lengthy but I took this method to understand better.