Q: A 2 kg block of aluminum (specific heat capacity $$c = 900\ \mathrm{J/kg\ ^\circ C}) is $$heated from $$20\ ^\circ C to$$ $$50\ ^\circ C. $$How much heat energy is required?

$$Q = 2 \times 900 \times (50-20) = 54,000\ \mathrm{J}$$

Q: A 5.0 μC charge and a 10.0 μC charge are placed 0.2 m apart in air. What is the magnitude of the force between them? ($$k = 8.99 \times 10^9$\ \mathrm{N\cdot m^2$/C^2$$}$)

$$F = 8.99 \times 10^9$ \times \frac{(5.0 \times 10$$^{-6}$$)(10.0 \times 10$$^{-6}$$)}{(0.2)^2$} = 1.12\ \mathrm{N}$$

Question 1

Which of the following best explains why the temperature of the ocean remains relatively stable throughout the year compared to land?

Accepted Answer

Because water's high specific heat capacity allows it to absorb or release large amounts of energy with little temperature change.

Question 2

A metal rod is heated at one end. Which process is primarily responsible for the transfer of heat to the other end of the rod?

Accepted Answer

Conduction

Question 3

A 2 kg block of aluminum (specific heat capacity $$c = 900\ \mathrm{J/kg\ ^\circ C}) is $$heated from $$20\ ^\circ C to$$ $$50\ ^\circ C. $$How much heat energy is required?

Accepted Answer

$$Q = 2 	imes 900 	imes (50-20) = 54,000\ \mathrm{J}$$

Question 4

Which of the following best describes why ice floats on water?

Accepted Answer

Ice has a lower density than liquid water because its molecules form an open crystal structure, increasing its volume by about 10%.

Question 5

A student rubs a balloon on their hair and then brings it near a wall. The balloon sticks to the wall. Which concept best explains this phenomenon?

Accepted Answer

The wall becomes electrically polarized due to the charged balloon, resulting in attraction.

Question 6

Which of the following statements about Coulomb's Law is correct?

Accepted Answer

It describes the electric force between two charges and is given by $$F = k \frac{q_1$ q_2$}{r^2$}.$$

Question 7

A 5.0 μC charge and a 10.0 μC charge are placed 0.2 m apart in air. What is the magnitude of the force between them? ($$k = 8.99 	imes 10^9$\ \mathrm{N\cdot m^2$/C^2$$}$)

Accepted Answer

$$F = 8.99 	imes 10^9$ 	imes \frac{(5.0 	imes 10$$^{-6}$$)(10.0 	imes 10$$^{-6}$$)}{(0.2)^2$} = 1.12\ \mathrm{N}$$

Question 8

Which of the following best describes why a current-carrying wire produces a magnetic field?

Accepted Answer

The moving electric charges in the wire create a magnetic field around the wire.

Question 9

A solar panel converts sunlight into electricity. Which process is primarily responsible for this energy conversion?

Accepted Answer

Photoelectric effect

Question 10

Which of the following best explains why ultraviolet light does not pass through glass, but visible light does?

Accepted Answer

Glass absorbs ultraviolet light but is transparent to visible light due to its atomic structure.

Question 11

A photon has a frequency $$f. $$According to Planck's equation, what is its energy?

Accepted Answer

$$E = hf$$

Question 12

Which of the following is a correct statement about the photoelectric effect?

Accepted Answer

Electrons are ejected from a metal only if the light has a frequency above a certain threshold, regardless of intensity.

Question 13

According to de Broglie, what is the wavelength $$\lambda$$ associated with a particle of momentum $$p$$?

Accepted Answer

$$\lambda = \frac{h}{p}$$

Question 14

Which of the following best describes the concept of quantum uncertainty?

Accepted Answer

It is impossible to know both the exact position and momentum of a particle at the same time.

Question 15

Which experiment provided evidence that atoms are mostly empty space with a dense nucleus?

Accepted Answer

Rutherford's gold foil experiment

Question 16

A spaceship travels at $$0.8c$$ relative to Earth. According to special relativity, what happens to the length of the spaceship as measured by an observer on Earth?

Accepted Answer

It appears contracted in the direction of motion.

Question 17

Which of the following is a consequence of Einstein's equation $$E=mc^2$?

Accepted Answer

Mass and energy are equivalent and can be converted into each other.

Question 18

A muon is created high in Earth's atmosphere and travels toward the ground at nearly the speed of light. Why does it reach the ground before decaying, even though its lifetime is very short?

Accepted Answer

Time dilation causes the muon's lifetime to appear longer to an observer on Earth.

Question 19

Which of the following best describes the correspondence principle?

Accepted Answer

Quantum physics and relativity agree with classical physics in the limit of large systems or low speeds.

Question 20

Which device is specifically designed to minimize heat transfer by conduction, convection, and radiation?

Accepted Answer

Thermos bottle (vacuum flask)

Physics 101: Key Concepts from Temperature to Relativity

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