Physics - Term 3 - Week 10

Kinematics is the branch of physics that describes the motion of objects. It focuses on the relationships between displacement, velocity, acceleration, and time. Displacement is the change in position of an object and is a vector quantity, meaning it has both magnitude and direction. Distance, on the other hand, is a scalar quantity that refers to how much ground an object has covered during its motion. Velocity is defined as the rate of change of displacement and can be calculated as the displacement divided by time. Acceleration is the rate of change of velocity and can be positive (speeding up) or negative (slowing down).

A car travels 100 meters east and then 50 meters west. To find the displacement, we consider the direction: Displacement = 100 m (east) - 50 m (west) = 50 m (east). This shows that displacement takes direction into account, unlike distance, which would simply be 150 meters.

Consider a runner who completes a 400-meter lap in 50 seconds. To find the average velocity, we use the formula: Velocity = Displacement / Time. Here, the displacement is 400 meters (since they return to the starting point) and the time is 50 seconds. Therefore, the average velocity is 400 m / 50 s = 8 m/s. Discuss with your peers how this differs from average speed.

A bicycle accelerates from rest to a speed of 20 m/s in 10 seconds. Calculate the acceleration using the formula: Acceleration = (Final Velocity - Initial Velocity) / Time. Here, the initial velocity is 0 m/s, the final velocity is 20 m/s, and the time is 10 seconds. Students should calculate the acceleration and reflect on how this relates to everyday experiences.

• The total path length traveled
• The shortest distance from the initial to the final position
• The speed of an object
• The rate of change of velocity

Answer: The shortest distance from the initial to the final position

Displacement is defined as the straight line distance from the starting point to the endpoint, along with its direction.

• Distance
• Speed
• Displacement
• Time

Answer: Displacement

Displacement is a vector quantity because it has both magnitude and direction, while distance is a scalar quantity.

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

Acceleration measures how quickly an object changes its velocity, which can involve speeding up, slowing down, or changing direction.

• It is increasing
• It is decreasing
• It is zero
• It is negative

Answer: It is zero

Constant velocity means that there is no change in speed or direction, which indicates that the acceleration is zero.

• 12 m/s²
• 10 m/s²
• 15 m/s²
• 20 m/s²

Answer: 12 m/s²

Acceleration is calculated as (Final Velocity - Initial Velocity) / Time = (60 m/s - 0 m/s) / 5 s = 12 m/s².

Answer: Average Speed = Total Distance / Total Time

Average speed is determined by dividing the total distance traveled by the total time taken.