please help me, with complete solutions

From the movie Tarzan: Lord of the Jungle, a 50-kg gorilla was in trouble. Upon sensing this situation, he comes to the rescue swinging from vine to vine. He adjusts the strong, but very lightweight vine so that he will first come to rest 4 seconds after beginning his epic swing. We assume further that he swung at the bottom end of the vine. (a) How long was Tarzan's vine? (b) What is the frequency of Tarzan's swing