Energy and Forces Unit Test
Question --- Answer
In models of magnetic and electric fields, why are field vectors depicted by arrows? --- because they represent both their magnitude and direction
A model depicts two balloons of the same size with identical negative charges being moved toward one another at the same speed. How will the balloons interact with each other? --- They will repel, moving in opposite directions at the same speed.
A model shows a machine that works using electrical fields. What would this machine need for the electrical field to function properly? --- at least two charged, interacting parts
Which diagram would represent kinetic energy and launched particles? --- an arrow released from the bow
During chemical reactions, bonds between atoms break and form. What does this mean in terms of subatomic particles? --- Electrical fields of charged particles interact, bonding those with opposite charges.
What is the driving force behind chemical reactions between elements? --- the interaction of the electric fields of protons and electrons
A community seeks to develop a maglev train operation. Which of the following is most likely their technical motivation for choosing this option? --- They seek a rail line not affected by friction.
The north and south poles of two magnets are attached to each other. A student pulls the poles apart and hold them at a distance of 10 cm. How does the energy stored in the system change? --- The energy stored in the system increases.
A student places two horseshoe magnets next to each other, and the poles of the magnets attach to each other. How does the kinetic energy of the system change? --- Kinetic energy increases because the magnets move in the direction of the field.
A giant magnet moves above a debris pile with many pieces of iron buried in it. Which statement is correct about the energy stored in the magnetic field? --- Iron pieces accelerate toward the magnet, and the energy stored in the system decreases.
The north pole of a bar magnet is moved close to the north pole of another bar magnet that is suspended by a thread. How does the energy stored in the magnetic field change? --- The energy stored in the field decreases because the magnet moves in the direction of the field.
Two magnets with like poles facing each other are brought close to each other and then released. How does the energy stored in the system change? --- The energy stored increases and then decreases.
Use the model to answer the question. The model shows a simple electromagnet that does not attract metal objects. (Picture) Which observation or inference is correct? --- The wire was not connected to the source.
Use the image to answer the question below. More coils are produced when the wire is wrapped tightly around the iron core. (Picture) What will happen to the property of the electromagnet with an increasing number of coils? --- The electromagnet will become more powerful.
What is the weak nuclear force? --- a force that governs how elements break down naturally
On which planet is gravity strongest? --- Jupiter
4 answers
In 3–4 sentences, describe how a particle accelerator works and give an example of the applications of the discoveries made with them.
---------------------------------------------------------------------------------------------------- Particle accelerators create a beam of charged particles. It can be used for so many different things, but a few specific things stand out. Particle accelerators have been used in many different ways to aid patients, it can help find the diagnostic or it can provide some sort of therapy for the patient to help them recover.
A magnet is removed from a refrigerator door and placed on a table. In 1–2 sentences, explain how the potential energy of the system changes in this process.
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When you pull a magnet off a refrigerator door, the potential energy increases because the farther the two charged objects move apart, the more charge they get.
Using a simple model of an electromagnet, describe the factors that increase the magnetic field strength of an electromagnet.
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Factors that affect the strength of electromagnets are the nature of the core material, strength of the current passing through the core, the number of turns of wire on the core and the shape and size of the core.
In 3-5 sentences, explain how gravity causes Earth's tides.
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The Moon and the Earth exert a gravitational pull on each other. On the Earth, the Moon's gravitational pull causes the oceans to bulge out on both the sides which are closest to the Moon and the sides farthest from the Moon. These bulges create the high tides. The low points of these tides are are the places where low tides occur. These bulges of water on the Earth are high tides. High tide on the left and low tide on the right can be observed in the Bay of Fundy in Canada.
17 - score 4/4 (teacher feedback: extra credit - skipped question)
18 - score 2/2
19 - score 2/2
20 - score 4/4