Motion in a Straight Line: Uniform Motion and Acceleration

Study Notes

Definition: Motion of an object in a straight line with a constant velocity (speed and direction).
Characteristics:
- Constant speed
- Constant direction
- No acceleration
- Distance-time graph is a straight line
- Velocity-time graph is a horizontal line
Examples:
- A car moving on a straight road with a constant speed
- A ball rolling on a flat surface with no friction

Definition: The rate of change of velocity with respect to time.
Characteristics:
- Increase in velocity
- Change in direction
- Force is applied in the direction of motion
- Distance-time graph is a curved line
- Velocity-time graph is a sloping line
Types of acceleration:
- Positive acceleration: increase in velocity (e.g., a car accelerating from rest)
- Negative acceleration: decrease in velocity (e.g., a car slowing down)

Definition: The rate of change of velocity in the opposite direction of motion, resulting in a decrease in velocity.
Characteristics:
- Decrease in velocity
- Force is applied in the opposite direction of motion
- Distance-time graph is a curved line
- Velocity-time graph is a sloping line with a negative slope
Examples:
- A car slowing down to stop
- A ball rolling on a rough surface, experiencing frictional force

Motion with constant velocity (speed and direction) in a straight line
Characteristics of uniform motion:
- Constant speed, no increase or decrease
- Constant direction, no change in path
- No acceleration, no change in velocity
- Distance-time graph is a straight line, indicating equal distances covered in equal time intervals
- Velocity-time graph is a horizontal line, indicating constant velocity
Examples of uniform motion:
- A car moving on a straight road with a constant speed, no acceleration or deceleration
- A ball rolling on a flat surface with no friction, maintaining constant velocity

Rate of change of velocity with respect to time, resulting in an increase in velocity
Characteristics of acceleration:
- Increase in velocity, resulting in faster motion
- Change in direction, possible with acceleration
- Force is applied in the direction of motion, causing acceleration
- Distance-time graph is a curved line, indicating unequal distances covered in equal time intervals
- Velocity-time graph is a sloping line, indicating increasing velocity
Types of acceleration:
- Positive acceleration: increase in velocity, e.g., a car accelerating from rest
- Negative acceleration: decrease in velocity, but not retardation, e.g., a car slowing down, but still moving forward

Rate of change of velocity in the opposite direction of motion, resulting in a decrease in velocity
Characteristics of retardation:
- Decrease in velocity, resulting in slower motion
- Force is applied in the opposite direction of motion, causing retardation
- Distance-time graph is a curved line, indicating unequal distances covered in equal time intervals
- Velocity-time graph is a sloping line with a negative slope, indicating decreasing velocity
Examples of retardation:
- A car slowing down to stop, experiencing a decrease in velocity
- A ball rolling on a rough surface, experiencing frictional force, resulting in a decrease in velocity