Conceptual Physics Chapter 3 Flashcards

Key Concepts in Linear Motion

• Speed: Defined as distance traveled per unit of time, indicating how fast an object moves.
• Velocity: Combines speed with a directional component, defining both how fast and in what direction an object moves.
• Vector Quantity: A physical quantity that possesses both magnitude (size) and direction, e.g., velocity and acceleration.
• Acceleration: Measures how quickly an object’s velocity changes, which can be due to a change in speed, direction, or both.
• Free Fall: Describes the motion of an object influenced only by gravity, without any other forces acting on it.

Equations and Calculations

• Speed Equation: Speed = Distance / Time.
• Average Speed Equation: Average Speed = Total Distance Covered / Time Interval.
• Acceleration Equation: Acceleration = Change of Velocity / Time Interval.
• Acceleration (along a straight line): A measure of the change in speed over time.
• Velocity in Free Fall: When falling from rest, velocity can be calculated using v = gt, where g is the acceleration due to gravity.
• Distance Fallen in Free Fall: Can be derived from d = ½ gt², representing how far the object falls over time.

Motion Characteristics

• Relative Motion: All motion is measured relative to a frame of reference.
• Linear Motion: Involves movement along a straight line.
• Instantaneous Speed: The speed of an object at any precise moment in time.
• Constant Velocity: Occurs when an object moves in a straight line at a uniform speed.
• Changing Velocity: Happens when there is a change in speed or direction (or both).

Average Speed and Examples

• Necessary Measurements: Average speed calculations require both distance and time.
• Example of Average Speed: A horse covering 10 km in 30 minutes has an average speed of 20 km/h.
• Acceleration Example: A car traveling at a constant velocity of 100 km/h for 10 seconds experiences zero acceleration.

Free Fall Dynamics

• Speed After 12 Seconds: An object in free fall from rest reaches speeds exceeding 100 m/s after 12 seconds.
• Increasing Fall Distance: Each second of free fall results in an increased distance fallen due to constant acceleration.
• Acceleration Consistency: Dropping a rock from heights of 5 m or 2.5 m shows that the acceleration due to gravity remains about the same.

Projectile Motion

• Upward Motion: A heavy object moving upward at 50 m/s will slow to about 40 m/s after 1 second due to gravity.
• Projectile Time to Top: For a projectile fired straight up at 10 m/s, reaching the peak takes approximately 1 second.

Understanding Acceleration

• Nature of Acceleration: It is defined as the rate at which an object's velocity changes over time, distinct from being merely a change in speed or velocity itself.