A wave is produced at one end of a rope the adjacent figure represents the shape of the rope at a certain instant t. A;B;C;D;E and F are six points vibrating on the rope
1- Name 2 points to determine the period and the wavelength
2- If A needs 0.02 sec to complete one vibration and distance between B and E is 4cm
A) what do, 0.02 sec and 4cm represent for the wave?
b) deduce the speed of the wave
C) calculate the distance between A and E

Amerry-go-round of radius r, shown in the figure, is rotating at constant angular speed. the friction in its bearings is so small that it can be ignored. a sandbag of mass m is dropped onto the merry-go-round, at a position designated by r. the sandbag does not slip or roll upon contact with the merry-go-round. how would you rank the following different combinations of m and r on the basis of the angular speed of the merry-go-round after the sandbag "sticks" to the merry-go-round from largest to smallest. a) m = 10kg, r = 0.25r b) m = 20kg, r = 0.25r c) m = 10kg, r = 0.50r d) m = 10kg, r = 1.0r e) m = 15kg, r = 0.75r f) m = 40kg, r = 0.25r