7.7 Motion and Forces Unit 2

Avery and Liam are on a road trip adventure! If their car zooms 150 kilometers in just 3 hours, can you guess their average speed?

• 45 km/h

• 50 km/h

• 55 km/h

• 60 km/h

Answer explanation

To find the average speed, divide the total distance by the total time. Here, 150 km ÷ 3 hours = 50 km/h. Therefore, the average speed of Avery and Liam is 50 km/h.

During a fun science class, Evelyn and Aria are debating: Which of the following best describes velocity?

• Speed in a given direction

• Distance covered per unit time

• The rate of change of speed

• The total distance traveled

Answer explanation

Velocity is defined as speed in a given direction, distinguishing it from speed, which is a scalar quantity. The other options describe different concepts related to motion but do not accurately define velocity.

Scarlett is training for a big race and completes a 400-meter lap in just 50 seconds. Can you calculate Scarlett's speed and help her track her progress?

• 6 m/s

• 7 m/s

• 8 m/s

• 9 m/s

Answer explanation

To find Scarlett's speed, divide the distance by time. Speed = Distance / Time = 400 meters / 50 seconds = 8 m/s. Therefore, the correct answer is 8 m/s.

Tags

NGSS.MS-PS3-1

Liam and Avery are racing toy cars. Liam says, 'My car's velocity is faster because it has both speed and direction!' How does velocity differ from speed?

• Velocity includes magnitude and direction, while speed only includes magnitude.

• Speed includes magnitude and direction, while velocity only includes magnitude.

• Velocity is always greater than speed.

• Speed is always greater than velocity.

Answer explanation

Velocity differs from speed in that velocity includes both magnitude and direction, while speed only considers magnitude. This is why Liam is correct in stating that his car's velocity is faster.

Imagine Evelyn is on a skateboard, gliding smoothly down the street. Which graph best represents her moving at a constant speed?

• A straight horizontal line

• A straight line with a positive slope

• A curved line

• A straight line with a negative slope

Answer explanation

Evelyn gliding smoothly indicates constant speed, represented by a straight line with a positive slope. This shows her position increasing over time, unlike a horizontal line (no movement) or curved/negative lines (changing speed).

Tags

NGSS.MS-PS3-1

Join Maya, Sophia, and Hannah on a journey to interpret the motion of an object from a distance-time graph. What does it mean when the line is as flat as a pancake?

• The object is moving at a constant speed.

• The object is accelerating.

• The object is decelerating.

• The object is stationary.

Answer explanation

When the line on a distance-time graph is flat, it indicates that the distance is not changing over time. This means the object is not moving, hence it is stationary.

Imagine Daniel and Mason are having a tug-of-war, but neither is winning. What happens to the rope when balanced forces act on it?

• The rope accelerates.

• The rope remains in its current state of motion.

• The rope changes direction.

• The rope decelerates.

Answer explanation

When balanced forces act on the rope, it does not accelerate, change direction, or decelerate. Instead, it remains in its current state of motion, illustrating Newton's first law of motion.

Tags

NGSS.MS-PS2-2

Analyze the effect of unbalanced forces on an object at rest.

• The object will remain at rest.

• The object will start moving.

• The object will move in the opposite direction.

• The object will change shape.

Answer explanation

Unbalanced forces acting on an object at rest will cause it to start moving. This is due to Newton's first law, which states that an object will remain at rest unless acted upon by a net external force.

Tags

NGSS.MS-PS2-2

Rohan the cyclist embarks on a thrilling 90 km journey, completing it in just 3 hours. Can you calculate his average speed?

• 25 km/h

• 30 km/h

• 35 km/h

• 40 km/h

Answer explanation

To find the average speed, divide the total distance by the total time. Rohan traveled 90 km in 3 hours. Average speed = 90 km / 3 h = 30 km/h. Therefore, the correct answer is 30 km/h.

Which of the following scenarios best illustrates Newton's First Law of Motion?

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