Physics - Term 1 - Week 8

Kinematics is the branch of physics that describes the motion of objects without considering the forces that cause the motion. Key concepts include displacement, which is the change in position of an object, and distance, which is the total path length traveled. Speed is a scalar quantity representing how fast an object moves, while velocity is a vector quantity that includes direction. Acceleration is the rate of change of velocity over time. Understanding these concepts is crucial for analyzing motion.

Consider a car that travels 100 meters east and then 50 meters west. To find the displacement, we calculate the net change in position. The displacement is 100 m (east) - 50 m (west) = 50 m east. This example illustrates how displacement differs from distance, which would simply be 150 meters in this case.

Let's work through a problem together. A cyclist accelerates from rest to a speed of 10 m/s in 5 seconds. To find the acceleration, we use the formula: acceleration = (final velocity - initial velocity) / time. Here, acceleration = (10 m/s - 0 m/s) / 5 s = 2 m/s². Now, try calculating the distance traveled during this time using the equation: distance = initial velocity × time + 0.5 × acceleration × time².

Now it's your turn to solve these problems on your own. 1) A car accelerates uniformly from 20 m/s to 50 m/s in 10 seconds. Calculate the acceleration and the distance traveled during this time. 2) An object falls freely from rest for 4 seconds. Determine the final velocity and the distance fallen. Show all your workings.

• Speed is a vector; velocity is a scalar.
• Speed includes direction; velocity does not.
• Speed is a scalar; velocity is a vector.
• Speed and velocity are the same.

Answer: Speed is a scalar; velocity is a vector.

Speed only measures how fast an object is moving, while velocity also includes the direction of motion.

Answer: Displacement is the shortest distance from the initial to the final position of an object, including direction.

Displacement is a vector quantity that considers the overall change in position.

• a = (v_f - v_i) / t
• d = v_i * t + 0.5 * a * t²
• v_f = v_i + a * t
• All of the above

Answer: All of the above

All these equations relate to motion and involve acceleration in different contexts.

Answer: d = v_i * t + 0.5 * a * t²

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

• Zero
• Constant
• Increasing
• Decreasing

Answer: Constant

Even though the speed is constant, the direction changes, resulting in centripetal acceleration.

Answer: Uniform acceleration means that the rate of change of velocity is constant over time.

In uniform acceleration, an object increases or decreases its velocity at a steady rate.

• Distance traveled
• Acceleration
• Displacement
• Speed

Answer: Acceleration