Q2 Interim Review

Discuss how the total amount of charge possessed by the system of two blocks before the charging process compares to the total charge of the system after the charging process.

• The total charge remains the same before and after the charging process.

• The total charge increases after the charging process.

• The total charge decreases after the charging process.

• The total charge is zero before and after the charging process.

Answer explanation

The total charge in a closed system is conserved. Therefore, the total charge possessed by the two blocks before the charging process is equal to the total charge after the charging process, confirming that it remains the same.

Can electrons move between the two blocks if they are not touching?

• Yes, electrons can move between the blocks without touching.

• No, electrons cannot move between the blocks without touching.

Answer explanation

No, electrons cannot move between the blocks without touching because they require a conductive path to transfer charge. Without contact, there is no way for electrons to flow from one block to another.

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A metal block has a charge of -10 units. What will happen when contact is made between the block and the grounding rod?

• Electrons will move from ground to block and the block becomes more negatively-charged.

• Electrons will move from block to ground and the block becomes neutral.

• Electrons will move from ground to block and the block becomes neutral.

• Electrons will move from block to ground and the block becomes more negatively-charged.

Answer explanation

When the metal block, which has a negative charge, contacts the grounding rod, electrons will flow from the block to the ground. This transfer of electrons neutralizes the block, resulting in a neutral charge.

What effect does the distance between objects have on their gravitational force?

• Gravitational force increases with distance.

• Gravitational force decreases with distance.

• Gravitational force remains constant regardless of distance.

• Gravitational force is not affected by distance.

Answer explanation

Gravitational force decreases with distance due to the inverse square law, which states that as the distance between two objects increases, the gravitational force between them diminishes.

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When a magnetic needle is placed in the Earth’s magnetic field, it __________ with the Earth’s __________ __________.

• aligns,

  electric field

• points,

  North Pole

• aligns,

  South Pole

• deflects,

  Equator

Answer explanation

When a magnetic needle is placed in the Earth’s magnetic field, it points towards the Earth's North Pole due to the magnetic forces acting on it, aligning with the magnetic field lines.

What tool measures the direction of a magnetic field?

• Voltmeter

• Compass

• Light bulb

• Ruler

Answer explanation

A compass is a tool that measures the direction of a magnetic field by aligning itself with the Earth's magnetic field, making it the correct choice among the options provided.

When a motor turns on – why does the loop turn?

• The battery pushes protons through the wire to produce electric current and cause magnetism.

• The battery causes the permanent magnet to move electrons and make an electric field.

• The battery moves electrons through the wire, creating a magnetic field, causing it to attract and repel from the poles of the permanent magnet.

• The permanent magnet moves and produces an electric current.

Answer explanation

The correct choice explains that the battery moves electrons through the wire, generating a magnetic field. This field interacts with the permanent magnet, causing attraction and repulsion, which makes the loop turn.

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If there is 2 N of gravitational force between two objects, and then the distance is doubled, what would be the new force?

• 1 N

• 4 N

• 1/4 N

• 1/2 N

Answer explanation

According to the inverse square law of gravitation, if the distance between two objects is doubled, the gravitational force becomes one-fourth. Thus, 2 N becomes 2 N / 4 = 1/2 N.

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A gravitational field is generated by any object that has what property?

• Mass

• Magnetism

• Charge

• Conductivity

Answer explanation

A gravitational field is generated by any object that has mass. Unlike magnetism, charge, or conductivity, mass is the fundamental property that creates a gravitational pull, affecting other masses in its vicinity.

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CALCULATOR QUESTION: What is the gravitational force between two 100 kg objects located 10 m from each other?

• 100 N

• 9*10^11 N

• 667 N

• 6.67*10^-9 N

Answer explanation

The gravitational force can be calculated using Newton's law of universal gravitation: F = G * (m1 * m2) / r^2. Here, G = 6.67*10^-11 N(m/kg)^2, m1 = m2 = 100 kg, and r = 10 m, resulting in F = 6.67*10^-9 N.

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