Question

(9) Dipueen - Didice llaveneu
A car moving on a straight road with speed 144 km/hr is brought to stop within a distance of 100 m. How long
does it take to stop (assuming uniform retardation) and if the speed of car is doubled, then stopping distance will
become respectively :-
(1) 5 s, 200 m
(2) 10 s, 400 m
(3) 5 s, 180 m
(4) 5 s, 400 m​

Answer 1

Answer:

5s,400m

Explanation:

144km/hr=144×5/18=40m/s

v=d/t

40=100/t

t=5/2s

2nd case

speed doubles,then time doubles (same retardation)

80m/s=d/t t=5/2×2 =5s

80=d/5

d=80×5

400m

answer (4) 5s,400m