When you walk with a cup of coffee (diameter5 cm) at just the

right pace of about1 step per second, the coffee builds up its

"sloshing" untileventually, after a few steps, it starts to spill

over the top. What is the speed of the waves in the coffee?

10 cm/sec

Explanation:

using formula velocity = frequency * wave length

where: f=1/T

1/1=1

so frequency will be 1HZ (due to 1 oscillation in 1 sec)

wave length will be 10 cm because while sloshing cup hold (1/2) half full length.

velocity = 1*10 = 10cm/sec.

velocity = 10 cm/sec