You create a pulse on a stretched spring by moving, with your hand, one part of the spring up and down once. The leading edge of the pulse travels a distance L in a time T. If you wanted to decrease T what could you do?

1. Move your hand further in the same time interval
2. Move your hand up and down the same distance in less time
3. Increase the tension in the spring
4. Use a spring with a smaller mass per unit length, but having the same tension
5. All of the above
6. 1 or 2
7. 3 or 4
8. 2, 3, or 4
9. Some other combination