Physics - Term 1 - Week 2

Kinematics is the branch of physics that deals with the motion of objects without considering the forces that cause the motion. Displacement is a vector quantity that refers to the change in position of an object. Velocity, also a vector, is the rate of change of displacement, while acceleration is the rate of change of velocity. Understanding these concepts is crucial for analyzing motion.

Motion can be represented graphically, and these graphs provide valuable insights into the behavior of moving objects. A displacement-time graph shows how an object's position changes over time, while a velocity-time graph indicates how the object's velocity changes. The slope of these graphs represents different physical quantities: the slope of a displacement-time graph gives velocity, and the slope of a velocity-time graph gives acceleration.

Consider a car that travels 100 meters east and then 50 meters west. To find the total displacement, we calculate: Displacement = Final position - Initial position = 100 m (east) - 50 m (west) = 50 m (east). This example illustrates how to determine displacement by considering direction.

Given a velocity-time graph where the velocity increases linearly from 0 m/s to 20 m/s over 5 seconds, we can find the acceleration. The slope of the graph (change in velocity/change in time) gives us acceleration = (20 m/s - 0 m/s) / (5 s - 0 s) = 4 m/s². This shows how to extract acceleration from a velocity-time graph.

A cyclist travels 150 meters in 10 seconds. To find the average velocity, we use the formula: Average Velocity = Total Displacement / Total Time. Here, Average Velocity = 150 m / 10 s = 15 m/s. Students should practice calculating average velocity with different distances and times.

Students will solve a set of problems involving displacement, velocity, and acceleration. For example, if a runner accelerates from rest to a speed of 10 m/s in 4 seconds, they should calculate the acceleration and the distance covered during this time. This exercise will reinforce their understanding of the concepts discussed.

• m/s
• m/s²
• km/h
• m

Answer: m/s²

Acceleration is defined as the change in velocity per unit time, which is measured in meters per second squared (m/s²).

• Speed
• Distance
• Velocity
• Time

Answer: Velocity

Velocity is a vector quantity, meaning it has both magnitude and direction, unlike speed and distance which are scalar quantities.

Answer: Displacement is the vector quantity that represents the change in position of an object.

Displacement considers both the distance and direction from the initial to the final position.

• 20 m east
• 100 m
• 20 m west
• 40 m east

Answer: 20 m east

Displacement is calculated as the final position minus the initial position, resulting in 20 meters east.

Answer: The slope of a velocity-time graph represents acceleration.

The slope indicates how quickly velocity changes over time, which is the definition of acceleration.

• 4 m/s²
• 3 m/s²
• 12 m/s²
• 0 m/s²

Answer: 4 m/s²

Acceleration is calculated as the change in velocity divided by the time taken: (12 m/s - 0 m/s) / 3 s = 4 m/s².

• v = u + at
• s = ut + 1/2 at²
• v² = u² + 2as
• F = ma

Answer: F = ma

F = ma is Newton's second law of motion, not a kinematic equation, which deals with motion without regard to forces.