Acheetah can run at top speed for only about 20 seconds. if an antelope is too far away for a cheetah to catch it in 20 seconds, the antelope is probably safe. your friend claims an antelope running 60 feet per second will not be safe if the cheetah running at 90 feet per second is 650 feet behind it. is your friend correct? for the antelope to not be safe, the cheetah would have to maintain top speed for about seconds. round to the nearest tenth.