QUESTIONS AND CORRECT DETAILED ANSWERS|ALREADY GRADED A+
Course
WGU C165 OA
1. Question:
Which of the following best describes the law of conservation of energy?
A. Energy is destroyed when it is used.
B. Energy can be created from nothing.
C. Energy can be converted from one form to another, but the total amount remains constant.
D. Energy is always in the form of motion.
Correct Answer: C
Rationale: The law of conservation of energy states that energy cannot be created or
destroyed; it can only be transferred or transformed into different forms (e.g., chemical energy
to kinetic energy). This principle applies to all physical systems, ensuring that the total energy
remains unchanged.
2. Question:
A car is moving at a constant speed of 60 mph on a straight road. According to Newton’s First
Law of Motion, what will happen if no external force is applied to the car?
A. The car will slow down and eventually stop.
B. The car will continue moving at 60 mph indefinitely.
C. The car will accelerate on its own.
D. The car will turn automatically.
Correct Answer: B
Rationale: Newton’s First Law (also called the law of inertia) states that an object in motion
stays in motion at a constant velocity unless acted upon by an external force (such as friction or
air resistance). Since no external force is mentioned, the car will continue moving at 60 mph
indefinitely.
3. Question:
Which of the following best describes how heat is transferred from the Sun to the Earth?
,A. Conduction
B. Convection
C. Radiation
D. Evaporation
Correct Answer: C
Rationale: Heat transfer from the Sun to the Earth occurs through radiation, which involves
electromagnetic waves (such as infrared and visible light). Since space is a vacuum, conduction
and convection are not possible.
4. Question:
Which of the following best explains why a metal spoon heats up when placed in a cup of hot
coffee?
A. Conduction
B. Convection
C. Radiation
D. Evaporation
Correct Answer: A
Rationale: Conduction is the process of heat transfer through direct contact. The spoon’s metal
atoms absorb thermal energy from the hot coffee and transfer it through the spoon via atomic
vibrations.
5. Question:
What happens to the motion of molecules when a substance is heated?
A. Molecules slow down and move closer together.
B. Molecules remain the same but expand in size.
C. Molecules move faster and spread apart.
D. Molecules disappear and new ones form.
Correct Answer: C
Rationale: When a substance is heated, its molecules gain kinetic energy, move faster, and
spread apart. This explains why most substances expand when heated.
,6. Question:
Which of the following best describes the role of gravity in the formation of stars?
A. Gravity pulls gas and dust together to form a star.
B. Gravity prevents stars from forming.
C. Gravity only affects planets, not stars.
D. Gravity causes stars to explode into black holes.
Correct Answer: A
Rationale: Gravity is the primary force responsible for the formation of stars. It pulls hydrogen
gas and dust together, increasing pressure and temperature until nuclear fusion ignites, forming a
star.
7. Question:
What happens when an object is accelerating?
A. Its velocity is changing.
B. It is moving at a constant speed.
C. It is always increasing in speed.
D. Its momentum remains unchanged.
Correct Answer: A
Rationale: Acceleration is defined as any change in velocity (speed or direction). This means
an object can accelerate by speeding up, slowing down, or changing direction.
8. Question:
A scientist is studying how different surfaces affect the speed of a rolling ball. What is the
independent variable in this experiment?
A. The type of surface
B. The speed of the ball
C. The weight of the ball
D. The distance the ball travels
Correct Answer: A
, Rationale: The independent variable is the factor that is deliberately changed by the scientist.
In this case, the type of surface (e.g., wood, carpet, tile) is the variable being manipulated to
observe its effect on the ball’s speed.
9. Question:
Why do astronauts in orbit around Earth experience weightlessness?
A. There is no gravity in space.
B. The Earth’s gravity is too weak at that altitude.
C. The spacecraft is in free fall, constantly falling toward Earth.
D. Astronauts lose mass in space.
Correct Answer: C
Rationale: Astronauts experience weightlessness because they are in free fall. The spacecraft
and astronauts inside are falling toward Earth at the same rate as their forward motion, creating a
sensation of floating.
10. Question:
Which of the following best explains why seasons occur on Earth?
A. The distance between Earth and the Sun changes during the year.
B. Earth rotates at different speeds at different times of the year.
C. The tilt of Earth's axis causes different parts of the planet to receive varying amounts of
sunlight.
D. The Moon’s gravity affects Earth’s temperature.
Correct Answer: C
Rationale: Seasons occur because Earth is tilted at approximately 23.5 degrees on its axis. As
Earth orbits the Sun, different hemispheres receive varying amounts of direct sunlight, creating
seasonal changes.
11. Question:
Which of the following is an example of a chemical change?
A. Ice melting into water
B. Water evaporating into steam