If velocity is positive, which would most likely yield a negative acceleration?
A. A final velocity that is faster than an initial velocity.
B. A time that is less than a half hour.
C. An initial velocity that is faster than a final velocity.
D. A time that is greater than a half hour.
please answer quickly

You have been hired to design a spring-launched roller coaster thatwill carry two passengers per car. the car goes up a 10-m highhill, then descends 15m to the track's lowest point. you'vedetermined that the spring can be compressed a maximum o 2.0m andthat a loaded car will have a maximum mass of 400kg. for safetyreasons, the spring constant should be 10% larger than the minimumneeded for the car to just make it over the top. a) what spring constant (k) should you specify ? b) what is the maximum speed of a 350 kg car if the spring iscompressed the full amount.