L3: Distance-Time Graphs (7.7C) [easy]

Which of the following distance-time graphs represents an object moving at a constant speed?

• A straight line with a positive slope

• A curved line

• A horizontal line

• A straight line with a negative slope

Answer explanation

A straight line with a positive slope indicates constant speed, as the distance increases uniformly over time. In contrast, a curved line shows changing speed, a horizontal line indicates no movement, and a negative slope represents movement in the opposite direction.

If an object’s distance-time graph is a horizontal line, what can be inferred about the object's motion?

• The object is moving at a constant speed.

• The object is accelerating.

• The object is not moving.

• The object is decelerating.

Answer explanation

A horizontal line on a distance-time graph indicates that the distance does not change over time, meaning the object is not moving. Therefore, the correct inference is that the object is not moving.

How can you differentiate between a graph showing constant speed and one showing changing speed?

• Constant speed graphs are curved, while changing speed graphs are straight.

• Constant speed graphs are straight lines, while changing speed graphs are curved.

• Both graphs are straight lines but with different slopes.

• Both graphs are curved but with different curvatures.

Answer explanation

A graph showing constant speed is represented by a straight line, indicating uniform motion. In contrast, a graph showing changing speed is curved, reflecting variations in speed over time. Thus, the correct choice is that constant speed graphs are straight lines, while changing speed graphs are curved.

Tags

NGSS.MS-PS3-1

An object travels 150 meters in 30 seconds. What is its average speed?

• 3 m/s

• 5 m/s

• 4 m/s

• 6 m/s

Answer explanation

To find average speed, divide distance by time. Here, average speed = 150 meters / 30 seconds = 5 m/s. Thus, the correct answer is 5 m/s.

Which of the following statements is true about a distance-time graph with a line that slopes downward?

• The object is moving away from the starting point.

• The object is moving towards the starting point.

• The object is stationary.

• The object is accelerating.

Answer explanation

A downward slope on a distance-time graph indicates that the distance from the starting point is decreasing, meaning the object is moving towards the starting point.

If a distance-time graph shows a line that becomes steeper over time, what does this indicate about the object's motion?

• The object is moving at a constant speed.

• The object is slowing down.

• The object is speeding up.

• The object is stationary.

Answer explanation

A steeper line on a distance-time graph indicates that the distance covered by the object is increasing at a faster rate over time, meaning the object is accelerating. Therefore, the object is speeding up.

Tags

NGSS.MS-PS3-1

Calculate the average speed of an object that travels 200 meters in 50 seconds.

• 2 m/s

• 4 m/s

• 5 m/s

• 6 m/s

Answer explanation

To find average speed, use the formula: speed = distance / time. Here, speed = 200 meters / 50 seconds = 4 m/s. Thus, the correct answer is 4 m/s.

What does the slope of a distance-time graph represent?

• The total distance traveled

• The speed of the object

• The time taken

• The acceleration of the object

Answer explanation

The slope of a distance-time graph indicates how much distance is covered over a specific time period, which directly represents the speed of the object. Therefore, the correct answer is 'The speed of the object'.

On a distance-time graph, what does a steeper slope indicate compared to a less steep slope?

• A slower speed

• A faster speed

• A longer distance

• A shorter time

Answer explanation

A steeper slope on a distance-time graph indicates that distance is changing more rapidly over time, which means the object is moving faster. Therefore, a steeper slope represents a faster speed.

Tags

NGSS.MS-PS3-1

If a distance-time graph shows a line that flattens out over time, what does this indicate about the object's motion?

• The object is moving at a constant speed.

• The object is speeding up.

• The object is slowing down.

• The object is stationary.

Answer explanation

A distance-time graph that flattens out indicates that the slope is decreasing, meaning the object is covering less distance over time. This shows that the object is slowing down.