# Work done by a swinging spring-like object [not homework]

1. Jan 19, 2010

### holezch

This isn't a homework problem, I'm just wondering: if you had a spring like object like a rubber band or just a spring, and attached something to its end and swung it across (like swinging a vine to get across a river), how do you compute the work? is it just -kx^2? where x is the displacement from the spring unstretched to its stretched state?

thanks

2. Jan 19, 2010

### dacruick

when you say work what do you mean. Do you meant he energy of the system? Do you mean the work done by gravity?

3. Jan 19, 2010

### holezch

oh , I meant the work done by the spring-like object

thanks!

4. Jan 19, 2010

### ideasrule

Yes, the work done by the rubber band alone is -kx^2.

5. Jan 19, 2010

### holezch

thanks , I thought so intuitively.. but I need to think about the definition of work. So, work is the displacement multiplied by the force done in the same direction.. and since the stretching or compressing on a spring is always on the same "axis" as the spring force, we can just say -k or k right?