Physics - Term 1 - Week 3

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 defined as the rate of change of displacement with respect to time. Acceleration is the rate of change of velocity over time. Understanding these concepts is crucial for analyzing the motion of objects.

Consider a car that travels 100 meters to the east in 5 seconds. The average velocity can be calculated using the formula: average velocity = total displacement / total time. Here, the average velocity = 100 m / 5 s = 20 m/s to the east. This example illustrates how to apply the formula to find average velocity in a straightforward scenario.

Let's work through an example together. A cyclist increases their velocity from 5 m/s to 15 m/s in 4 seconds. To find the acceleration, we use the formula: acceleration = (final velocity - initial velocity) / time. Substituting the values, we get acceleration = (15 m/s - 5 m/s) / 4 s = 2.5 m/s². Now, try calculating the acceleration if the cyclist's final velocity was 20 m/s instead.

Analyze the motion graph provided in your handout. Identify the segments where the object is at rest, moving with constant velocity, and accelerating. Write a brief description of the motion during each segment. This exercise will help reinforce your understanding of how to interpret motion graphs and relate them to the concepts of displacement, velocity, and acceleration.

• m/s
• m²/s
• kg/m
• N

Answer: m/s

Velocity is measured in meters per second (m/s), which indicates how far an object travels in a given time.

• Change in velocity over time
• Distance over time
• Speed in a direction
• Total distance covered

Answer: Change in velocity over time

Acceleration is defined as the rate of change of velocity with respect to time.

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

Displacement considers both the distance and direction of the object's movement.

• It is increasing
• It is decreasing
• It is zero
• It is constant

Answer: It is zero

When an object moves with constant velocity, it means there is no change in velocity, hence the acceleration is zero.

Answer: Average velocity = total displacement / total time

This formula allows us to find the average velocity of an object over a specific time interval.

• 3 m/s²
• 6 m/s²
• 0.3 m/s²
• 30 m/s²

Answer: 3 m/s²

Acceleration is calculated as (final velocity - initial velocity) / time = (30 m/s - 0 m/s) / 10 s = 3 m/s².

Answer: Speed is a scalar quantity that refers to how fast an object is moving, while velocity is a vector quantity that includes both speed and direction.

This distinction is important in physics as it affects how we analyze motion.