Question

A wave travels a distance of 60cm in 3s. The distance blw successive crests of thd wave is 4cm. What is the frequency?

Answer 1

Data:
ΔS = 60cm
Δt = 3s
Vm = ?

Vm = ΔS/Δt 
$Vm = \frac{60}{3}$
$Vm = 20cm/s$

We have:

Vm = v
ΔS = λ
Δt = T

$v = \frac{\lambda}{T}$
$20 = \frac{\lambda}{4}$
$\lambda = 20*4$
$\lambda = 80cm$

Soon:

$v = \lambda*f$
$20 = 80*f$
$80f = 20$
$f = \frac{20}{80} simplify( \frac{\div20}{\div20} )= \frac{1}{4}$
$\boxed{f = 0,25Hz}$