Question

7) A 40kg mass is shot from a cannon at 50 m/s. The cannon recoils at 2 m/s. What is the mass of the cannon? ) A stranded 105kg man is motionless on a frozen, frictionless pond. To get to the shore, he throws his 10ke backpack at 2 m/s away from the shore. How fast does the man move? b) if the pond is 30m away, how much time will it take for the man to get to the shore? 9) A raft filled with the captain and gear has a mass of 3000kg is on the frozen, frictionless pond. The captain throws a 400kg box away from the shore at 0.5 m/s a) How fast does the raft move? b) How much time will the raft take to get to the shore 30m away?

Answer 1

By com implies 40 times 50 = m times 2 implies m = 20 times 50 m = 1000 kg mass of cannon. (8) (a) again by com implies 10 times 2 = 105 times V V = 20/ 105 m/ s or V = 0.19 m/ s (b) by V = d/ t implies t = d/ V = 30 times 105/ 20 sec t = 157.5 sec (a) by com implies 400 times 0.5 = (3000 - 400) V V = 0.077 m/s (b) by V = d/t implies t = d/ v = 30/ 0.077 t = 389.6 sec.