solution:
u=10m/s
a=a
v=30m/s
S=4km=4000m
v2-u2=2as
900-100=2a*4000
800=8000a
a=0.1m/s2
then,
v=u +at
30=10+0.1*t
30-10=0.1t
20=0.1t
t=200s
The time taken is 200s.
6.A car moving with a velocity of 10m/s and with a uniform acceleration gains a velocity of 30m/s after travelling a distance of 4km.The time taken is