Frequency in two different wires

[LandOfStandar]

I need help comprehending this one

Homework Statement

An aluminum wire. of length L1=60.0cm, cross-section area 1.00 x 10^-2 cm^2, and density 2.60g/cm^3, is joined to a steel wire, of density 7.80g/cm^3 and the same cross-section area. The compound wire, loaded with a block of mass m-10.0kg, is arranged so that the distance L2=86.6cm. Transverse waves are set up on the wire by an external source of variable frequency; a node is located at the pulley. (a) Find the lowest frequency that generates a standing wave having the joint as one of the nodes. (b) How many nodes are observed at this frequency?

Homework Equations

and

The Attempt at a Solution

f= v/(wavelength) = (n x v)/(2L)
v= (F/(linear density))

I know the F is 10.0kg x 9.80m/s^2 = 98.0N
...for the velocities do you do them saperate or together
...how do you get the wavelength

 

[BigJDubs]

? Attempt at a Solution: To solve this problem, we need to calculate the velocity of the wave on the aluminum wire and the steel wire. We can then use this velocity to calculate the wavelength and frequency of the wave. The velocity of the wave on the aluminum wire is given by v = F/linear density, where F is the force (98N) and linear density is the mass per unit length of the wire (2.60g/cm^3). Therefore, v = 98 N / (2.60 g/cm^3) = 37.69 m/s. The velocity of the wave on the steel wire is given by v = F/linear density, where F is the force (98N) and linear density is the mass per unit length of the wire (7.80g/cm^3). Therefore, v = 98 N / (7.80 g/cm^3) = 12.56 m/s. The wavelength of the wave is given by wavelength = (2L)/n, where L is the total length of the wire (L1+L2=146.6 cm) and n is the number of nodes present in the wave. To find the lowest frequency that generates a standing wave having the joint as one of the nodes, we need to use the equation f = v/(wavelength). Therefore, f = (37.69 m/s)/((2 x 146.6 cm)/1) = 0.51 Hz. There are two nodes present at this frequency, since the joint is one of the nodes.