QUESTION 143
A car travels at a constant speed of 90 km/h. The time, in hours, for this car to travel 270 km is
(A) 2
(B) 3
(C) 4
(D) 5
(E) 6

You have been hired to synchronize the four traffic lights on an avenue, indicated by the letters O, A, B, and C, as shown in the figure.
The traffic lights are separated by a distance of 500 m. According to statistical data from the traffic control company, a vehicle that is initially stopped at traffic light O typically starts with constant acceleration of $1 \mathrm{~m~s}^{-2}$ until reaching a speed of $72 \mathrm{~km~h}^{-1}$, and from then on, proceeds at constant speed. You must adjust traffic lights A, B, and C so that they change to green when the vehicle is 100 m away from crossing them, so that it does not have to reduce speed at any moment.
Considering these conditions, approximately how long after the opening of traffic light O should traffic lights A, B, and C open, respectively?
(A) $20 \mathrm{~s}, 45 \mathrm{~s}$ and $70 \mathrm{~s}$.
(B) $25 \mathrm{~s}, 50 \mathrm{~s}$ and $75 \mathrm{~s}$.
(C) $28 \mathrm{~s}, 42 \mathrm{~s}$ and $53 \mathrm{~s}$.
(D) $30 \mathrm{~s}, 55 \mathrm{~s}$ and $80 \mathrm{~s}$.
(E) $35 \mathrm{~s}, 60 \mathrm{~s}$ and $85 \mathrm{~s}$.

A parachutist after bailing out falls 50 m without friction. When parachute opens, it decelerates at $2 \mathrm{~m}/\mathrm{s}^2$. He reaches the ground with a speed of $3 \mathrm{~m}/\mathrm{s}$. At what height, did he bail out?
(1) 91 m
(2) 182 m
(3) 293 m
(4) 111 m