High School Physics : Understanding Scalar and Vector Quantities

Study concepts, example questions & explanations for High School Physics

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Example Questions

Example Question #31 : High School Physics

Which of the following is a vector?

Possible Answers:

Surface area

Temperature

Acceleration

Thermal energy

Distance

Correct answer:

Acceleration

Explanation:

Remember, vectors need both magnitude and direction. Acceleration is the only answer choice that requires both magnitude and direction.

Example Question #32 : High School Physics

A dog starts next to his owner, runs  to chase a ball, and then runs back  to the person who threw it. If this happens eight times to completion, what is the dog's displacement?

Possible Answers:

Correct answer:

Explanation:

Displacement is a vector quantity that describes final positive relative to the starting point. It only measures the change in distance from where you start to where you end up.

Since the dog runs away, and then runs back to his original starting point, he is going a total displacement of zero meters for every loop. Since he makes eight full circuits, he will start and end in exactly the same place, hence,  displacement.

Distance is the scalar equivalent for displacement; the dog's distance traveled with be .

Example Question #33 : High School Physics

A dog runs  to chase a ball and then runs back  to the person who threw it. If this happens eight times to completion, what is the dog's distance travelled?

Possible Answers:

Correct answer:

Explanation:

Unlike displacement, which only measures the change between starting point and ending point, distance measures the entire trip travelled. Displacement is a vector, while distance is a scalar; thus, displacement is independent of path, while distance is dependent on path.

Each circuit the dog travels a total of , and he makes this trip eight times.

He will travel a total distance of .

The total displacement would be zero because the dog's ending position does not change, relative to his starting position.

Example Question #31 : High School Physics

Which of the following is not a vector quantity?

Possible Answers:

Acceleration

Force

Volume

Velocity

Displacement

Correct answer:

Volume

Explanation:

Vector quantities have both magnitude and direction, while scalar quantities have only magnitude.

Velocity, acceleration, force, and displacement are all vectors. They must have a magnitude, as well as a direction of action. A velocity can be to the north, and a displacement can be east. A good way to identify vectors is if they can be negative. A negative vector indicates "downward" or "to the left," while a negative scalar cannot exist.

Volume is not a vector; it cannot have a direction. An object cannot have a volume of to the left, not can it have a volume of .

Example Question #35 : High School Physics

Which of the following is a vector quantity?

Possible Answers:

Electric potential

Voltage

Force

Resistance

Charge

Correct answer:

Force

Explanation:

A vector quantity is described by both its magnitude, and its direction of action. In contrast, a scalar quantity is described only by its magnitude.

Force is a vector because the direction of action is relevant to describing the force. An upward force is notably different from a downward force.

Voltage, resistance, charge, and electric potential are scalar quantities and are the same regardless of any direction of action. For example, turning a circuit sideways does not alter the values for any of these quantities.

Example Question #11 : Understanding Scalar And Vector Quantities

Which of these is used to describe both scalar and vector quantities?

Possible Answers:

Mass

Acceleration

Direction

Magnitude

Constants

Correct answer:

Magnitude

Explanation:

Vector quantities are defined by both a direction and a magnitude. Force, velocity, acceleration, and momentum are all vectors.

Scalar quantities are defined only by a magnitude. Mass, time, speed, and voltage are all scalars.

Vector and scalar quantities both require a magnitude.

Example Question #12 : Understanding Scalar And Vector Quantities

Which of these is not a vector quantity?

Possible Answers:

Displacement

Force

Torque

Mass

Angular momentum

Correct answer:

Mass

Explanation:

A scalar quantity can be defined by magnitude alone, but a vector quantity has both magnitude and direction of action. Mass is a scalar quantity because it does not act in any particular direction. The phrase "five kilograms east" is nonsense, indicating the mass cannot be a vector.

Angular momentum, force, displacement, and torque are all vector quantities and describe a value applied in a certain direction.

Example Question #12 : Understanding Scalar And Vector Quantities

Two vectors each have a magnitude of . Consider the range of possible lengths of the vector sum (resultant vector) of the two vectors, depending on their directions. What is the difference in magnitude between the largest possible length and the smallest possible length of the resultant vector?

 

Possible Answers:

Correct answer:

Explanation:

The largest possible length of the vector sum of the two vectors results when the vectors are oriented in the same direction. In this scenario, the resultant vector will have a length equal to the sum of the magnitudes of the two vectors.

The smallest possible length of the vector sum results when the vectors are oriented in opposite directions. In this scenario, the resultant vector will have a length equal to the different in magnitude between the two vectors.

The largest magnitude of the resultant vector is and the smallest is . Now we need to find the difference between these magnitudes.

Example Question #13 : Understanding Scalar And Vector Quantities

Which of the following is a vector quantity?

Possible Answers:

Weight

Density

Mass

Distance

Volume

Correct answer:

Weight

Explanation:

Scalar quantities are defined by a magnitude with no applicable direction. In contrast, vector quantities must have both magnitude and direction of action.

Mass, distance, density, and volume are all scalar quantities, simply defined by a magnitude. It impossible to have a directional mass or density, such as "5 kilograms east" or "0.6 grams per liter clockwise." Distance is the scalar form of displacement. Displacement accounts for the direction of a length measurement, while distance measures only the magnitude of the length.

Weight is defined as the force of gravity on an object. All forces are vector quantities.

Example Question #14 : Understanding Scalar And Vector Quantities

Distance is a scalar quantity. What vector quantity represents a distance in an applied direction?

Possible Answers:

Mass

Velocity

Displacement

Weight

Acceleration

Correct answer:

Displacement

Explanation:

Scalar quantities are defined by a magnitude with no applicable direction. In contrast, vector quantities must have both magnitude and direction of action.

Distance is a measure of length, taking into account all lengths covered in a path away from a starting point. Displacement is the vector equivalent of distance. Displacement measures length in a given direction from the starting point, without taking into account the path traveled. A car could travel a distance of 400 meters, but if it ultimately returns to its starting position its displacement will be zero.

Velocity is a vector that measure change in displacement per unit time. A force vector, such as weight, results when an acceleration vector (such as gravity) is applied to a mass. Mass itself is a scalar quantity.

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