String 1 in the figure has linear density 1.8 g/m and string 2 has linear densit
ID: 2066371 • Letter: S
Question
String 1 in the figure has linear density 1.8 g/m and string 2 has linear density 3.9 g/m. A student sends pulses in both directions by quickly pulling up on the knot, then releasing it. Consider the pulses are to reach the ends of the strings simultaneously.
What should the string length L1 be?
What should the string length L2 be?
Explanation / Answer
the tension (F) is equal in both strings the linear density of the strings u1=1.8g/m, u2=3.9g/m the sppeed of the pulse at the string v=Lenght/time=sqrt(F/u) --> t1=L1/(sqrt(F/u1) t2=L2/sqrt(F/u2) L1=4-L2 t1=t2 from above equations: L1/(sqrt(F/u2)=L2/sqrt(F/u1) L1=L2*sqrt(u1/u2) --> 4-L2=L2*sqrt(u1/u2)=L2*sqrt(0.5) --> L2=2.34 m --> L1=4-2.34=1.65m