Motion in One Direction

Why is it important to define a frame of reference when describing motion?

• It provides a consistent measurement of motion relative to a specific point.

• It allows for the measurement of motion in different units.

• It standardizes the speed of all objects being observed.

• It is only necessary for measuring time, not distance.

Answer explanation

Defining a frame of reference is crucial as it provides a consistent measurement of motion relative to a specific point, allowing for accurate descriptions and comparisons of how objects move.

Which of the following best explains why distance traveled can be greater than displacement?

• Distance includes the total path traveled, while displacement is only the straight-line distance between two points.

• Distance accounts for time taken, while displacement does not.

• Displacement is the same as velocity, while distance measures speed.

• Distance and displacement are always equal, but measured in different units.

Answer explanation

Distance includes the total path traveled, accounting for all movement, while displacement measures only the straight-line distance between the starting and ending points, making distance potentially greater than displacement.

Which of the following situations demonstrates the difference between speed and velocity?

• An object moves in a circle at constant speed but has changing velocity.

• An object remains at rest, so its speed and velocity are both zero.

• An object accelerates in a straight line, so its speed and velocity are identical.

• An object slows down, meaning its speed is negative while its velocity rema

Answer explanation

The correct choice illustrates that an object moving in a circle maintains constant speed but its direction changes, resulting in varying velocity. This highlights the distinction between speed (magnitude) and velocity (magnitude and direction).

What is the key difference between instantaneous speed and average speed?

• Instantaneous speed is measured over a longer time period, while average speed is measured at one specific moment.

• Average speed accounts for changes in velocity, while instantaneous speed remains constant.

• Instantaneous speed measures speed at a specific moment, while average speed is measured over a period of time.

• Instantaneous speed requires displacement, while average speed uses distance.

Answer explanation

The correct choice highlights that instantaneous speed is the speed at a specific moment, while average speed is calculated over a duration, capturing the overall distance traveled divided by the total time.

Which of the following statements best reflects the importance of accuracy in measuring velocity?

• Accurate measurements ensure that displacement and distance are always equal.

• Accurate velocity measurements require consistent frame of reference, precise time, and distance data.

• Accuracy in velocity can only be achieved when speed is constant.

• Accuracy in velocity is unimportant as long as the general direction is correct.

Answer explanation

The correct choice emphasizes that accurate velocity measurements depend on a consistent frame of reference, as well as precise time and distance data, which are essential for determining velocity accurately.

Why is displacement considered a vector, while distance is a scalar quantity?

• Displacement requires direction, while distance does not.

• Displacement is measured in different units than distance.

• Distance changes with time, but displacement is constant.

• Distance measures speed, while displacement measures velocity.

Answer explanation

Displacement is a vector because it has both magnitude and direction, indicating the shortest path from the starting point to the endpoint. In contrast, distance is a scalar quantity that only measures the total path length, regardless of direction.

A passenger on a moving train throws a ball straight up into the air. From the passenger's perspective, the ball goes up and comes straight down. From an observer outside the train, how does the ball appear to move?

• The ball follows a straight vertical path.

• The ball follows a straight horizontal path.

• The ball follows a curved path, combining upward motion and forward motion.

• The ball appears stationary in the air.

Answer explanation

From the outside observer's perspective, the ball moves upward while also maintaining the train's forward velocity, resulting in a curved path that combines upward motion and forward motion.

How can an object maintain constant speed but have a changing velocity?

• By moving in a straight line at a constant rate.

• By moving in a circle or any curved path.

• By stopping and starting again at the same speed.

• By accelerating in the same direction as its velocity.

Answer explanation

An object can maintain constant speed while changing velocity by moving in a circle or curved path. This is because velocity includes direction, and changing direction while keeping speed results in a change in velocity.

If an object moves from point A to point B in a straight line, but then returns to point A following a curved path, what is the object’s total displacement?

• Equal to the total distance traveled.

• Equal to the distance between points A and B.

• Equal to zero.

• Equal to half the total distance traveled.

Answer explanation

The object's total displacement is equal to the straight-line distance from the starting point A to the ending point A. Since it returns to the original position, the total displacement is zero.

If an object moves from point A to point B in a straight line, but then returns to point A following a curved path, what is the object’s total displacement?

• Equal to the total distance traveled.

• Equal to the distance between points A and B.

• Equal to zero.

• Equal to half the total distance traveled.

Answer explanation

The object's total displacement is equal to the straight-line distance from the starting point A to the ending point A. Since it returns to the original position, the total displacement is zero.