L2: Understanding Distance and Displacement (7.7B)

Which of the following best describes the difference between distance and displacement?

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

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

• Distance includes direction, while displacement does not.

• Distance is always equal to displacement.

Answer explanation

The correct choice states that distance is the total path traveled, while displacement is the shortest path between two points. This highlights the key difference: distance is scalar and path-dependent, whereas displacement is vector and direction-dependent.

A car travels 100 km north and then 50 km south. What is the car's displacement?

• 150 km

• 50 km north

• 50 km south

• 100 km north

Answer explanation

The car travels 100 km north and then 50 km south. To find displacement, subtract the southward distance from the northward distance: 100 km - 50 km = 50 km north. Thus, the correct answer is 50 km north.

Which of the following statements correctly differentiates speed from velocity?

• Speed is a vector quantity, while velocity is a scalar quantity.

• Speed includes direction, while velocity does not.

• Speed is the rate of change of distance, while velocity is the rate of change of displacement.

• Speed is always greater than velocity.

Answer explanation

The correct choice states that speed is the rate of change of distance, while velocity is the rate of change of displacement. This highlights that speed is a scalar quantity, whereas velocity is a vector quantity that includes direction.

Palmer completes a 400 m lap around a track in 50 seconds. What is Palmer's average speed?

• 8 m/s

• 4 m/s

• 0 m/s

• 2 m/s

Answer explanation

To find average speed, use the formula: speed = distance/time. Here, distance = 400 m and time = 50 s. Thus, average speed = 400 m / 50 s = 8 m/s. Therefore, the correct answer is 8 m/s.

Tags

NGSS.MS-PS3-1

A cyclist travels 30 km east and then 40 km west. What is the cyclist's total distance traveled?

• 70 km

• 10 km

• 40 km

• 30 km

Answer explanation

The cyclist travels 30 km east and then 40 km west. The total distance is the sum of both distances: 30 km + 40 km = 70 km. Therefore, the correct answer is 70 km.

In which scenario is velocity more appropriate to use than speed?

• Calculating the time taken to complete a marathon.

• Determining the direction and rate of a storm's movement.

• Measuring the distance covered by a car in an hour.

• Estimating the time to fill a swimming pool.

Answer explanation

Velocity is a vector quantity that includes direction, making it essential for determining the direction and rate of a storm's movement, unlike speed, which only measures how fast something is moving.

A person walks 3 km north, then 4 km east. What is the person's displacement?

• 7 km

• 5 km northeast

• 5 km

• 1 km

Answer explanation

The person walks 3 km north and 4 km east, forming a right triangle. Using the Pythagorean theorem, displacement = √(3² + 4²) = √25 = 5 km. The direction is northeast, making the correct answer 5 km northeast.

If a car travels at a constant speed of 60 km/h for 2 hours, what is the total distance covered by the car?

• 120 km

• 60 km

• 30 km

• 180 km

Answer explanation

To find the distance, 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 total distance covered by the car is 120 km.

Which of the following is an example of velocity?

• 50 km/h

• 30 m/s north

• 10 m/s

• 5 km

Answer explanation

Velocity includes both speed and direction. '30 m/s north' specifies a speed of 30 meters per second in a specific direction (north), making it a clear example of velocity. The other options lack direction.

A train moves 100 km east and then 100 km west. What is the train's displacement?

• 200 km

• 0 km

• 100 km east

• 100 km west

Answer explanation

The train moves 100 km east and then 100 km west, returning to its starting point. Displacement measures the shortest distance from the initial to the final position, which is 0 km.