Lab617

Answers to Practice Activity 6

1a. Analysis
There is an elastic interaction between the rubber band and the beanbag block.
The rubber band is the source and it decreases in stored elastic energy. The source transfers mechanical energy to the receiver which is the beanbag block. The beanbag block increases in motion energy.

1b. Explanation:
The beanbag block speeds up because mechanical energy is transferred to the beanbag block from the rubber band during this elastic interaction. The beanbag block increases in motion energy and the rubber band decreases in stored elastic energy.

2a. Analysis
There is a friction interaction between the block and the table.
The block is the source and it decrease in motion energy. Both the block and the table are the receivers and they increase in thermal energy.

2b. Explanation:
The block slows down because mechanical energy is transferred from the block to the table. The block and table warm up, increasing their thermal energy, and the block slows down, decreasing its motion energy.

posted by The Professor @ 4:55 PM 0 comments

SCI: The Mechanical Interaction

Here are the ideal responses for the SCI on the Mechanical Interaction:

Defining Characteristics of the Mechanical Interaction:
2. You should be able to come up with evidence for this from your teams set-up to U2C2 Activity 2 when your team demonstrated the 4 different types of mechanical interactions with toys.

Types of Mechanical Interactions and the Variables that Influence Them:
Friction Mechanical Interaction:
7a. Evidence for this statement would be from objects traveling across the floor vs. your lab table (which is rougher in texture) or across carpet or sandpaper.
7b. Evidence could be from when you rubbed your hands together in two different situations: pressed together lightly and pressed together firmly. When rubbed together in the second case, the hands become warmer than in the first case. Since the hands are warmer, the friction interaction must be stronger.

Drag Mechanical Interaction:
9a. For example, a marble dropped in thick shampoo falls more slowly than a marble dropped in water. The drag interaction is stronger for the thicker liquid.
9b. For example, when waving a notebook through the air, more air is moved when moving the cover of the notebook against the air then when waving the spine of the notebook through the air.
9c. For example, you feel more resistance from the air as you ride your bike faster (or stick a hand slightly outside a car's window as the car goes faster).

Elastic Mechanical Interaction:
11a. In the video, when the tennis ball strikes the racquet strings the ball slows down, the ball compresses and the strings stretch. The ball's motion energy decreases while the ball and the strings increase in stored elastic energy.
12a. In the experiment with the rubber band and the car, the more the rubber band was stretched, the farther the car was launched.
12b. For example, if you pull back on a rubber band it is harder to move a band that is stiffer or more firm. This indicates that the stretchiness (or stiffness) of an object affects the elastic interaction.

posted by The Professor @ 4:34 PM 0 comments