Physics - Term 3 - Week 1

Kinematics is the branch of physics that describes the motion of objects without considering the forces that cause the motion. The three key concepts in one-dimensional motion are displacement, velocity, and acceleration. Displacement is the change in position of an object and is a vector quantity, meaning it has both magnitude and direction. Velocity is the rate of change of displacement and can be average or instantaneous. Acceleration, also a vector quantity, is the rate of change of velocity over time.

Consider a car that travels 150 meters to the east in 5 seconds. To find the average velocity, we use the formula: average velocity = total displacement / total time. Here, the total displacement is 150 meters and the total time is 5 seconds. Thus, average velocity = 150 m / 5 s = 30 m/s to the east.

A cyclist increases their speed from 10 m/s to 25 m/s in 5 seconds. To find the acceleration, we use the formula: acceleration = (final velocity - initial velocity) / time. Substituting the values, we have acceleration = (25 m/s - 10 m/s) / 5 s = 3 m/s². Students should practice similar problems using different initial and final velocities.

Students will analyze a motion graph showing an object moving in a straight line. They will identify intervals of constant velocity, acceleration, and rest. For example, if the graph shows a straight line with a positive slope, the object is moving with constant velocity. If the slope increases, the object is accelerating. Students should create their own graphs based on given scenarios and describe the motion represented.

• Meters
• Seconds
• Kilograms
• Newtons

Answer: Meters

Displacement is measured in meters, which is the standard unit of length in the International System of Units (SI).

• A scalar quantity
• A vector quantity
• Always positive
• None of the above

Answer: A vector quantity

Velocity is a vector quantity because it has both magnitude and direction.

Answer: Acceleration is the rate of change of velocity over time.

Acceleration indicates how quickly an object is speeding up or slowing down.

• Zero
• Constant
• Increasing
• Decreasing

Answer: Zero

An object at rest has no change in position, hence its velocity is zero.

Answer: Average velocity = total displacement / total time.

This formula allows us to calculate how fast an object is moving on average over a given time period.

• Constant speed
• Acceleration
• Rest
• None of the above

Answer: Rest

A flat line indicates that the object is not changing its position, meaning it is at rest.

• Final velocity - initial velocity
• Final velocity + initial velocity
• Change in velocity / time
• None of the above

Answer: Change in velocity / time

Acceleration is calculated by taking the change in velocity and dividing it by the time taken for that change.