Review 1

What is a scalar quantity?

• A quantity that has both magnitude and direction

• A quantity that has only magnitude

• A quantity that has only direction

• A quantity that changes over time

Answer explanation

A scalar quantity is defined as one that has only magnitude, meaning it can be described by a numerical value alone, without any direction. This distinguishes it from vector quantities, which have both magnitude and direction.

Which of the following is a vector quantity?

• Temperature

• Speed

• Velocity

• Mass

Answer explanation

Velocity is a vector quantity because it has both magnitude and direction, unlike temperature, speed, and mass, which are scalar quantities that only have magnitude.

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

How is distance different from displacement?

• Distance is a vector quantity, while displacement is a scalar quantity.

• Distance is the shortest path between two points, while displacement is the total path traveled.

• Distance is the total path traveled, while displacement is the shortest path between two points.

• Distance and displacement are the same.

Answer explanation

Distance refers to the total length of the path traveled, while displacement is the straight line from the starting point to the endpoint, representing the shortest distance between them.

Calculate the speed of a car that travels 150 km in 3 hours.

• 45 km/h

• 50 km/h

• 55 km/h

• 60 km/h

Answer explanation

To find the speed, divide the distance by time: 150 km ÷ 3 hours = 50 km/h. Therefore, the correct answer is 50 km/h.

Which formula represents the relationship between speed, distance, and time?

• Speed = Distance × Time

• Speed = Distance ÷ Time

• Speed = Time ÷ Distance

• Speed = Distance + Time

Answer explanation

The correct formula is Speed = Distance ÷ Time. This means speed is calculated by dividing the distance traveled by the time taken, establishing the fundamental relationship between these three variables.

If a runner completes a 400 m lap in 50 seconds, what is their average speed?

• 6 m/s

• 7 m/s

• 8 m/s

• 9 m/s

Answer explanation

To find average speed, divide distance by time. Here, the runner covers 400 m in 50 s. Average speed = 400 m / 50 s = 8 m/s. Thus, the correct answer is 8 m/s.

Which of the following is an example of a scalar quantity?

• Force

• Acceleration

• Energy

• Displacement

Answer explanation

Energy is a scalar quantity as it has magnitude only, while force, acceleration, and displacement are vector quantities that have both magnitude and direction.

A cyclist travels 30 km north and then 40 km east. What is the magnitude of the displacement?

• 50 km

• 70 km

• 10 km

• 35 km

Answer explanation

The cyclist's path forms a right triangle with legs of 30 km and 40 km. Using the Pythagorean theorem, displacement = √(30² + 40²) = √(900 + 1600) = √2500 = 50 km. Thus, the magnitude of the displacement is 50 km.

What is the definition of a vector quantity?

• A quantity that has only magnitude

• A quantity that has only direction

• A quantity that has both magnitude and direction

• A quantity that changes over time

Answer explanation

A vector quantity is defined as one that has both magnitude and direction, distinguishing it from scalar quantities, which have only magnitude. Therefore, the correct answer is that a vector quantity has both magnitude and direction.

If a car travels at a speed of 60 km/h for 2 hours, what distance does it cover?

• 100 km

• 120 km

• 140 km

• 160 km

Answer explanation

To find the distance covered, use the formula: Distance = Speed × Time. Here, Speed = 60 km/h and Time = 2 hours. Thus, Distance = 60 km/h × 2 h = 120 km. Therefore, the correct answer is 120 km.