Paddle Paddle Paddle!

The day we took this picture Erika and I had paddling and we came back to school and Justin and Gavin were there. They took our paddles and tried to practice their strokes while sitting on the table. I never really thought of it at the time, but the reason why they didn't go anywhere, even with Gavin's big muscles and Justin's expert steering skills, was because the forces pushing back on the paddles weren't great enough to overcome the weight of the table. If they had been in the water they would have gone really far because of the water pushing back against the paddle, and because of the way the canoe is built and because of its weight. This is Newton's Third Law, for every action there's an equal and opposite reaction. The weight of the table makes the forces applied by the paddles almost negligible.

WORK iT

Shucks. All the pictures uploaded backwards. Anyway. Today Erika, Justin, and I worked on our physics journals at my house and on my hill. We focused mainly on work and potential and kinetic energy. I chose work because I wanted to set up my punching bag. As you can see in the bottom picture, Justin is struggling to hold up the 100 lb punching bag by himself. Even though he's having a LOT of trouble holding it up, he's not doing any work. Why not? Because work requires force and motion in the direction of the force. Because Justin is holding the punching bag in place, he's not changing the position at all, although he's getting tired, he's doing no work. In the second, third, and fourth pictures, Justin and I are raising the punching bag to hang it up onto the chains. We are doing work in these pictures because we are lifting the punching bag, therefore applying force and displacing the punching bag, changing its position. When we actually started punching the bag, we were using energy, another new concept we learned. When Justin and I punched the bag, the energy put into the punch did not simply disappear, it was absorbed by the punching bag and turned into a different form of energy. The law of conservation of energy states that energy is neither created nor destroyed. I'm not quite sure where the energy went, but because we're in physics I can confidently say that it must still exist!