Question

what is the duration during which the car moves with constant velocity?​

Answer 1

Correct option is (A)

175 m

For constant velocity : 

Constant velocity  u=10 m/s

Time  t=10 s

So, displacement in 10 seconds  S1=ut=10×10=100 m

For accelerated journey :

Initial speed  u=10 m/s

Acceleration  a=2 m/s2

Time  t=5 s

Displacement in 5 seconds,   S2=ut+21at2

⟹ S2=10×5+21×2×52=75 m

Total displacement in 15 seconds  Stotal=100+75=175 m