Physics - Term 4 - Week 1

Kinematics is the branch of physics that deals with the motion of objects without considering the forces that cause the motion. The three fundamental concepts 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, indicating how quickly an object is speeding up or slowing down.

A car travels 100 meters east and then 50 meters west. To find the total displacement, we calculate the net change in position. The displacement is 100 m (east) - 50 m (west) = 50 m east. This example illustrates how to consider direction when calculating displacement.

Consider a runner who completes a 400-meter lap in 50 seconds. To find the average velocity, we use the formula: average velocity = total displacement / total time. Here, the total displacement is 400 meters (since the runner returns to the starting point) and the total time is 50 seconds. Thus, the average velocity is 400 m / 50 s = 8 m/s. Discuss with your peers how the direction of motion affects the velocity.

Now, solve the following problems on your own: 1) A car accelerates from rest to 20 m/s in 5 seconds. Calculate the acceleration. 2) A bike moving at 10 m/s comes to a stop in 2 seconds. What is the acceleration? Remember to use the formula: acceleration = (final velocity - initial velocity) / time.

• 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 measures how far out of place an object is; it is the shortest distance from the initial to the final position.

• Speed
• Distance
• Velocity
• Time

Answer: Velocity

Velocity includes both magnitude and direction, making it a vector quantity, while speed is only magnitude.

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

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

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

Answer: It is zero.

Constant velocity means there is no change in speed or direction, hence acceleration is zero.

Answer: Average velocity = total displacement / total time.

This formula allows us to find the average velocity over a given time interval.

• 15 m/s
• 30 m/s
• 150 m/s
• 0 m/s

Answer: 15 m/s

Average speed is calculated as total distance divided by total time, which is 150 m / 10 s = 15 m/s.

• Constant speed
• Acceleration
• No movement
• Deceleration