Physics Chapter on Motion Concepts

Multiple Choice and True/False

• Distance vs. Displacement: Distance is the total path traveled, while displacement measures the change in position from the starting point. (Question 1, a is correct).

• Time to Cover Distance: If speed is known, time = distance/speed. To travel 210.0m east at 5.9 m/s it takes 210.0 m / 5.9 m/s = 35.6 seconds (Question 2, b is correct)

• Position-Time Graph Slope: The slope of a position-time graph represents velocity (Question 3, c is correct).

• Vector vs. Scalar: Velocity is a vector (having both magnitude and direction), while speed is a scalar (having only magnitude) (Question 4, c is correct).

• Starting Position Calculation: If final distance and change in distance are known, the starting position can be calculated as follows: Starting Position = Final Distance – Change in Distance In this case, that would be 19.8 m - 7.3 m = +12.5 m. (Question 5, b is correct)

• Velocity from Acceleration: Velocity = Final velocity = Initial Velocity + (Acceleration × Time). Velocity = 0 m/s + (9.8 m/s² × 2.2 s) = 21.56 which is approximately 22 m/s (Question 6, a is correct).

• Position-Time Graph Information: A position-time graph allows determination of distance and displacement (Question 7, c is correct).

• Velocity with Positive/Negative Acceleration: If initial velocity is positive and acceleration is negative, velocity decreases (Question 8, a is correct).

• Acceleration Definition: Acceleration is the rate of change of velocity (Question 9, b is correct).

• Speed vs. Velocity Difference: Speed is the magnitude of velocity, while velocity also specifies direction. Velocity changes when either speed or direction or both change.

• Velocity-Time Graph Slope: A positive slope on a velocity-time graph indicates increasing velocity (positive acceleration), (Question 11, T).

• Distance is Scalar: Distance is a scalar quantity, always a positive value (Question 12, T)

• Circular Motion Average Velocity: If an athlete runs around a circular track and returns to the starting position, the average velocity is zero, because the net displacement is zero. (Question 13, T).

• Comparing Speeds: 55 km/h is the faster speed compared to -55 km/h. Positive values or negative values for speed or velocity depend on direction relative to the positive direction of the chosen axis system. (Question 14, T).

• Position-Time Graph Horizontal Line: A horizontal line on a position-time graph means the object is stationary (speed is zero), (Question 15, T).

• Velocity-Time Graph Horizontal Line: Zero slope on a velocity-time graph means constant velocity, not acceleration (Question 16, T).

• Distance/Displacement for Speed/Velocity: Distance is used to determine speed, and displacement is used to determine velocity. (Question 17, T)

• Calculating Distance: Time multiplied by velocity will give you the distance covered. (Question 18, F)

• Position Definition Position is the location of an object relative to a reference point. A is correct. (Question 19, C is correct).

• Final Velocity: Final velocity (v2) is the velocity at the end of an interval. (Question 20, C is correct).

• Initial Velocity: Initial velocity (v1) is the velocity at the beginning of an interval.(Question 21, A is correct).

• Vector Definition: A vector is a quantity having both magnitude and direction. (Question 22, A is correct).

• Average Velocity: Average velocity is displacement divided by time. (Question 23, A is correct).

• Velocity-Time Graph Area: The area under a velocity-time graph represents the displacement. (Question 24, B is correct)

• Instantaneous Velocity: Instantaneous velocity is the velocity at a particular moment in time. (Question 25, C is correct).

Part B: Diagrams (Position-Time Graph Analysis)

• Position at 5 seconds: (Answer needed from the diagram)
• Average velocity (first 11 seconds): (Answer needed from the diagram)
• Forward Motion Intervals: (Answer needed from the diagram)
• Backward Motion Intervals: (Answer needed from the diagram)
• Rest Intervals: (Answer needed from the diagram)
• Displacement (6s to 14s): (Answer needed from the diagram)
• Average Velocity (2s to 6s): (Answer needed from the diagram)

Part C: Problem Solving

• Average Velocity (Part C, Question 1): Average velocity = total displacement / total time. To calculate this you need the total displacement and total time for the trip. This requires the diagram information not provided above.
• Cheetah Distance (Part C, Question 2): Distance = speed × time Distance = (110 km/hr) × (5.0 s) = 550 km-s/hr (convert seconds to hours if needed as well) Additional information is required to solve for distance.
• Distance Traveled (Part C, Question 3): (Answer needed from the diagram)
• Displacement (Part C, Question 3): (Answer needed from the diagram)
• Speed (Part C, Question 3): Speed = total distance / total time = (Total distance from the diagram) / 100 seconds.
• Velocity (Part C, Question 3): Velocity = displacement / time = (net displacement from the diagram) / 100 seconds.
• Runner's Time (Part C, Question 5): Time = distance / speed = 47.9 m / 8.77 m/s = 5.46 seconds.