Physics - Term 3 - Week 2

Kinematics is the branch of physics that describes the motion of objects without considering the forces that cause the motion. The three fundamental quantities in kinematics 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 is the rate of change of velocity over time. Understanding these concepts is crucial for analyzing motion.

A car 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 displacement is 150 m and the time is 5 s. Thus, average velocity = 150 m / 5 s = 30 m/s to the east. This example illustrates how to calculate average velocity using displacement and time.

Consider a runner who starts from rest and accelerates uniformly at 2 m/s² for 10 seconds. First, calculate the final velocity using the formula: final velocity = initial velocity + (acceleration × time). Since the initial velocity is 0, final velocity = 0 + (2 m/s² × 10 s) = 20 m/s. Next, find the displacement using the formula: displacement = initial velocity × time + 0.5 × acceleration × time². Therefore, displacement = 0 + 0.5 × 2 m/s² × (10 s)² = 100 m. This exercise helps reinforce the application of kinematic equations.

Students will complete a set of problems that require them to calculate displacement, velocity, and acceleration in various scenarios. For example, if a cyclist travels 200 meters in 8 seconds, what is their average velocity? Students should apply the relevant formulas and show their work for full credit. This practice will solidify their understanding of kinematic concepts.

• The total distance traveled by an object.
• The change in position of an object.
• The speed of an object in a given direction.
• The rate of change of velocity.

Answer: The change in position of an object.

Displacement is defined as the change in position of an object and is a vector quantity.

• Speed
• Distance
• Velocity
• Time

Answer: Velocity

Velocity is a vector quantity because it has both magnitude and direction, unlike speed and distance.

Answer: 20 m/s

Average velocity = total displacement / total time = 300 m / 15 s = 20 m/s.

• 2 m/s²
• 4 m/s²
• 5 m/s²
• 10 m/s²

Answer: 4 m/s²

Acceleration = (final velocity - initial velocity) / time = (30 m/s - 10 m/s) / 5 s = 4 m/s².

Answer: displacement = initial velocity × time + 0.5 × acceleration × time²

This formula accounts for both the initial velocity and the effect of constant acceleration over time.

• 0 m/s
• 10 m/s
• 5 m/s
• It cannot be determined.

Answer: 0 m/s

An object at rest has an initial velocity of 0 m/s.

• A straight line with a positive slope.
• A straight horizontal line.
• A curve that gets steeper.
• A straight line with a negative slope.