Chalk Smashing Ability

We first reviewed from yesterday. We discussed that we needed a push or pull in other words a force. We also said that the directoin of the force and displacement had to be going in the same direction to have CSA (chalf smashing abilities).

Why does it matter to talk about both diplacement and force?

We said that it was both important because even if we give some things force it may not be able to be diplaced.

Ex. Yuji tried to push the table fixed to the ground. It didn't move and couldn't get CSA

Finley then forced the dictionary up but he diplaced the object sideways. The dictionary did not get CSA.

We then disucussed what happened with me pushing the desk and Finley displacing and forcing in a different direction.

For me pushing the table I couldn't diplace it because it was fixed to the floor. For the dictionary going in different directions the force and displacement was going in different ways so the dictionary could not get CSA.

We then experimented with this theory. We had Hleb as the chalk smashing machine and Daphnie was part of the Chalk Liberation Movement. Hleb pushed the cart at the chalk and Daphnie pushed the opposite direction to save it.

Here is the results

Hleb: 10 units of CSA

Daphne:-10 units of CSA

Daphne + Hleb: 0 units of CSA

So expressed as a number sentence 10-10=0
Yay! Daphnie saved the chalk!

We then did this again with Finley and Hleb and this time because Finley did not push as hard to stop the displacement the cart still got CSA. We now had to revisit the first hypothesis that force and displacement had to go the same way for a object to got CSA.

This is what we came up with.

New Hypothesis: When the force and displacement is going the same direction increases the CSA. When the displacement and force are going opposite directions the CSA decreases.

Finley then gave us another puzzling question.
Where did the CSA come from?

A good guess was that it came living things. This was disproved when Finley pushed a cart into another cart and gave it CSA. The cart had given the cart CSA.

We concluded that it came from a external source of energy.

We then defined work.
Work- when we transfer energy to or from another object or system.
We can either do positive or negative work on the system.
Ex. Daphnie did negative work to the cart when it was trying to gain CSA.

We then discussed what was initial state and final state.
Initial state: where it started
Final state: where it ended up after the work

Ex. Finley lifts book
Initial state: Sitting on table
Final state: In the air in Finley's hand

We now set about to try to show how much energy the book had and got after it was lifted.
We said that the book already had 10 units of energy. After it was picked up it had 30 units of energy. Finley had to do 20 units of work in order to achieve this.

HW: Look on Finley's website

YS