Question

Four students determined velocity of a pulse in a slinky. They found that the pulse took 7.5 seconds to complete three times the length of the slinky which is 15m. The velocity of the pulse calculated by them is:

a) 6.5 m/s b) 6.0 m/s c) 7.5 m/s d) 3.5 m/s

Answer 1

three times the length of slinky = 3× 15 m
= 45m
speed=distance/ time=45/7.5= 6 m/s

Answer 2

time taken to complete 3 times =7.5 seconds
time taken to complete 1 time =7.5/3
=2.5 seconds
velocity= wavelength ×frequency
velocity=wavelenght×1/time period (as f =1/t)
=15×1/2.5
=6.0 m/s

hope it helps..