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.
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.
S.C.I.: Speed of Objects and Waves - Ideal Responses
Speed of Waves
5.
In the video, it appeared that the speed of transverse and compressional Slinky waves didn't change when the frequency or amplitude of the waves was changed. The simulation in the video shows that the speed of sound waves doesn't change with frequency or amplitude, but changes in different materials (or media, substances).6.
The simulation in the video shows that sound waves travel more quickly through steel (solid) than through water (liquid), and more quicky through water than through air (gas). Evidence also comes from the measured speeds of sound in different media in different phases listed in the table in Activity 7.
S.C.I.: The Mechanical-Wave Interaction - Ideal Responses
Defining Characteristics of the Mechanical-Wave Interaction
3.
When we watched the transverse and mechanical waves produced on the slinky, we observed that the string attached to the Slinky did not move along the length of the Slinky, rather it moved with the disturbance as the disturbance went by. After the disturbance (or pulse) went by, the string was back in its original position.Types of Mechanical-Wave Interactions and Variables That Influence Them
7.
When the person vibrating the Slinky back and forth increased the rate of vibration (the frequency), we saw that the wavelengths got shorter.8.
When the person vibrating the Slinky back and forth increased the distance from the starting position (the amplitude), it felt as if it took more energy to generate the wave, and the person at the receiving end said if felt as if the Slinky hit their hand more strongly - that the Slinky was transferring more energy to their hand.
Scientists' Consensus Ideas - Ideal Responses
I. The Magnetic Interaction2. In Exploration #1, a second magnet either moved toward or away from the first magnet. After the first magnet was turned over, the 2nd magnet moved the opposite way.3. Exploration #2 supports this idea. We observed that when a magnet was moved close to nickel and steel (iron), they moved towards the magnet.4. In Exploration #2 we observed that the interaction was the same whichever side of the magnet was used.5. U1C1Act.3 - The Paper Clip Experiment (The larger the magnet, the larger the distance from which a paper clip will move toward a magnet.)II. The Electic-Charge Interaction2. In Exploration #1, when we charged up a balloon we found that it attracted objects (both metal and non-metal) with no charge.3. In Exploration #2, when we brought two pieces of charged tape near each other, each with the same charge, the repelled each other. They did this even when we turned one or both pieces of tape around.4. In Exploration #2, when we brought two pieces of charged tape near each other, each with a different charge, they attracted each other. They did this even when we turned one or both pieces fo tape around.5. In Exploration #1, when we brought small pieces of metal (aluminum foil) and non-metal (paper) near a charged object (balloon), they were both attracted to the the charged object.III. The Electric-Circuit Interaction1. In Explorations #1 and #3, bulbs lit up when they were connected in a complete loop to a battery. Bulbs did not light up when the circuit loop they were in was broken.2. In Exploration #1, the bulb lit up when the circuit loop was completed.3. Conductors: iron nail, steel washer, aluminum foil, pencil lead Non-conductors: paper, plastic pen cap, glass marble, rubber eraser, wood, cotton clothing, clay, ceramic mug5. In Exploration #4, when we put more batteries in the circuit, the bulbs lit brighter. Also, the more batteries in the simulator circuit in Exploration #5, the greater the elctric current.6. In Exploration #3, when we unscrewed a bulb from its socket, all the bulbs went out in the series circuit, but only the unscrewed bulb went out in the parallel circuit.IV. Electromagnets and Electromagnetic Interaction3. In the experiment done in Activity 5, the electromagnet (a nail with a wire wrapped around it) could pick up more washers when either the current in the wires was increased (more cells), the number of turns of wire wrapped around the nail was increased, or the coils were compressed closer together on the nail. The electromagnet was also stronger when the coil of wire was wrapped around a nail than when it wasn't.
1st Period: Practice Activity 5 Answers
I know that I have your papers, but I will type the complete correct answers for each question.
1. "d) The longer the pendulum, the less time it takes to swing back and forth" is the statement that is
not true.
11 people missed this question!2. "e) An uncharged object can have different numbers of positive and negative charges" is the statement that is
not true.
19 people missed this question!3."c) an electrical switch" is
not required for an electric-circuit interaction.
1 person missed this question.4. "c) You must have two magnets to have a magnetic interaction" is the statement that is
not true.
9 people missed this question!5. "b) The two objects move toward each other" is evidence for an electric-charge interaction between a charged object and an uncharged object.
15 people missed this question!6. "a) Add more cells in the series circuit" would make the electrical current increase.
2 people missed this question.7. To make an electromagnet you would "e) Wrap a coil of wire around a magnetic material, then connect the coil in a circuit to a source of elecrticity."
8 people missed this question!
DRY MIX
A little bit about manipulated and responding variables...
First, note that a "variable" is anything that can change in an experiment. Some variables change during the experiment, most do not.
The variable that you intentionally change (on purpose!) is the "manipulated variable" (remember, you are manipulating it). The variable that responds to that change is called the "responding variable". If it helps, the "responding variable" is almost always going to be the variable that we collect data for in an experiment.
For example, lets say that we are going to do an experiment to test the relationship between the mass of the pendulum and the amount of time it takes to swing back and forth ten times. To do this, we might decide to add more washers to the end of the pendulum. We will do three trials each for one washer, two washers and three washers and record the time the pendulum takes to swing back and forth ten times. What would the manipulated and responding variables be?
Well, the manipulated variable (MV) would be the number of washers on the pendulum because this is the variable that we are changing deliberately. The responding variable (RV) would then be the time it takes to swing back and forth ten times.
A "controlled variable" is any variable that does not change during an experiment. Remember, only the MV and the RV can change if the experiment is to be a fair test.
Finally, try and use DRY MIX to help you remember the variables and graphing.
Dependent
Responding
Y-axis
Manipulated
Independent
X-axis
See you in class...
Mr. D
