a. the -3.5t indicates it is moving in the +x direction.
consider some time t+epsilon after time t. Consider the peak of the wave, so (2.2x-3.5t) is 90 degrees. at time t+e, 2.2x-3.5t-3.5e has to be 90 deg, so x has to increase to keep the max.
b.,c: http://www.animations.physics.unsw.edu.au/jw/travelling_sine_wave.htm
The wave function (x,t)=(0.03m)sin(2.2x-3.5t) is for a harmonic wave on a string. (a) In what direction does this wave travel and what is its speed? (b) Find the wavelength, frequency, and period of this wave. (c) What is the maximum displacement of any point on the string? (d) What is the maximum speed of any point on the string?
2 answers
it is y(t) not (x,t)
y is a function of time
to stay on the same spot on the wave
2.2 x - 3.5 t
must be constant
that will happen if
x = (3.5/2.2) t
well, what does that look like ?
distance = speed * time :)
so go right at 3.5/2.2 = 1.59 meters/second
at t = 0 and x = 0, y = 0
when is the argument changed by 2pi at x = 0 ?
3.5 t = 2 pi
t = 2 pi/3.5 = T the period in seconds
similarly where is the argument changed by 2 pi at t = 0?
2.2 x = 2 pi
x = 2 pi/2.2 = Lambda the wavelength in meters
sin or cos can never be bigger than one so max y = 0.02 meter
frequency = 1/T in Hz
max speed = max of dy/dt = 0.03 * 3.5
y is a function of time
to stay on the same spot on the wave
2.2 x - 3.5 t
must be constant
that will happen if
x = (3.5/2.2) t
well, what does that look like ?
distance = speed * time :)
so go right at 3.5/2.2 = 1.59 meters/second
at t = 0 and x = 0, y = 0
when is the argument changed by 2pi at x = 0 ?
3.5 t = 2 pi
t = 2 pi/3.5 = T the period in seconds
similarly where is the argument changed by 2 pi at t = 0?
2.2 x = 2 pi
x = 2 pi/2.2 = Lambda the wavelength in meters
sin or cos can never be bigger than one so max y = 0.02 meter
frequency = 1/T in Hz
max speed = max of dy/dt = 0.03 * 3.5
1 answer