# Simple harmonic motion question

1. May 15, 2010

### 123mock

hi i am having trouble grasping this question

A block of mass M hangs from a rubber cord. The block is supported so that the cord is not stretched. The unstretched length of the cord is L0, and its mass is m, much less than M. The "spring constant" for the cord is k. The block is released and stops momentarily at the lowest point.

(a) Determine the tension in the string when the block is at this lowest point. (Use the following variables as necessary: L_0 for L0, m, M, and g.)
(b) What is the length of the cord in this "stretched" position? (Use the following variables as necessary: L_0 for L0, k, m, M, and g.)
(c) If the block is held in this lowest position, find the speed of a transverse wave in the cord. (Use the following variables as necessary: L_0 for L0, k, m, M, and g.)

doing this question with the spring is much easier, but the rubber cord is confusing.

2. May 15, 2010

### Andrew Mason

I am having trouble understanding why you find it much easier with spring. Just pretend it is a spring and solve it. Then substitute the words "rubber cord" for "spring" in your answer.

AM