# The pulling or pushing

You pull the rope to set the rope everywhere in the loop moving. The rope does not slide through your hands so you exert a grip force on the rope. You can't easily set rope loops going by pushing, but either a push or a pull is a force changing movement.

### Choosing a battery

Batteries push and pull to set charge moving. Choose a different battery to cage this flow. Batteries are marked to show how much they will push or pull the charge to set it flowing. This making is a certain number of volts (V). You could expect to find batteries around the house at 1.25 V, 1.5 V, 3 V, 9 V. Car batteries are 12 volts. Choose a battery marked with more volts to get a bigger push. But bigger batteries might not push more.

### Running down a battery

Larger batteries can push for longer before being completely run down because the battery stores more chemicals. How hard they push and how long they can push for are different. Some batteries have another mark on the side to show how big their store is. The marking might be 41 Wh, for example.

And some are rechargeable so that you can re-stock their store.

### AC

Some sources push, then pull, then push again, and so on. The mains electric circuits are like this. But the rope loop can still help you think about these loops.

And the AC? It stands for alternating current.