Physics - Term 2 - Week 3

Kinematics is the branch of physics that describes the motion of objects. It involves concepts such as displacement, which is the change in position of an object, and distance, which is the total path length traveled. 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. Acceleration is the rate of change of velocity over time. Understanding these concepts is crucial for analyzing motion.

Consider a car that travels 60 meters east, then 40 meters west. To find the displacement, we calculate the net change in position. The car's initial position is 0 m, and after traveling east, it is at +60 m. After moving west, its position is 60 m - 40 m = 20 m. Therefore, the displacement is 20 meters east.

A cyclist travels 100 meters in 5 seconds. To find the average velocity, we use the formula: velocity = displacement/time. Here, the displacement is 100 m, and the time is 5 s. Thus, the average velocity is 100 m / 5 s = 20 m/s. Students should now calculate the average velocity for a runner who covers 200 meters in 10 seconds.

Students will solve the following problems on their own: 1) A car accelerates from rest to 25 m/s in 5 seconds. Calculate the acceleration. 2) A ball is thrown upwards with an initial velocity of 15 m/s. How high does it go before it starts to fall back down? Use the equation h = (v^2)/(2g) where g = 9.8 m/s².

• Speed is a vector; velocity is a scalar.
• Speed includes direction; velocity does not.
• Speed is a scalar; velocity is a vector.
• There is no difference.

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

Speed measures how fast an object moves regardless of direction, while velocity includes both speed and direction.

• 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: Displacement is the vector quantity that represents the change in position of an object.

Displacement considers the initial and final positions, taking direction into account.

• a = v/t
• a = (v_f - v_i)/t
• a = d/t
• a = v_i + at

Answer: a = (v_f - v_i)/t

Acceleration is defined as the change in velocity (final minus initial) divided by the time taken.

Answer: Meters per second squared (m/s²).

Acceleration is measured in meters per second squared, indicating how much velocity changes per second.

• 50 m/s
• 75 m/s
• 100 m/s
• 30 m/s

Answer: 50 m/s

Average speed is calculated by dividing the total distance by the total time: 150 m / 3 s = 50 m/s.

• 20 m/s