a 2kg block hangs from a rubber cord. the block is supported so that the cord is not stretched. the unstretched length is .5m and its mass is 5g. the spring constant is 100 N/m. The block is released and stops at the lowest point. a) determine the tension in the cord when the block is at this lowest point b) hat is the length of the cord in the stretched position c) find the speed of a transverse wave in the cord if the block is held at this lowest position.(adsbygoogle = window.adsbygoogle || []).push({});

a) i said that the tension in the string is the same as mg

so T = mg

T = (2kg)(9.8m/s^2)

T = 19.6 N

the back of the book says the answer is 39.2 N, which is double mine. The teacher said something about conservation of energy but i still cant figure out where that factor of two comes in :(

i know how to do b) and c), but they depend on a) so of course they come out wrong too. :(

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Tension of a rubber cord problem

**Physics Forums | Science Articles, Homework Help, Discussion**