Physics - Term 1 - Week 9

Kinematics is the branch of physics that deals with the motion of objects without considering the forces that cause the motion. Displacement refers to 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 measures the total path length traveled by an object. Velocity is the rate of change of displacement and can be calculated as the change in position over time. Acceleration is the rate of change of velocity and can be positive (speeding up) or negative (slowing down).

Consider a car that travels 100 meters east and then 50 meters west. To find the displacement, we calculate the net change in position: Displacement = 100 m (east) - 50 m (west) = 50 m (east). To find the average velocity if the journey takes 10 seconds, we use the formula: Velocity = Displacement / Time = 50 m / 10 s = 5 m/s (east).

A cyclist accelerates from rest to a speed of 15 m/s in 5 seconds. To find the acceleration, we use the formula: Acceleration = (Final Velocity - Initial Velocity) / Time. Here, Initial Velocity = 0 m/s, Final Velocity = 15 m/s, and Time = 5 s. Therefore, Acceleration = (15 m/s - 0 m/s) / 5 s = 3 m/s². Students should now try calculating the acceleration for a car that goes from 20 m/s to 50 m/s in 10 seconds.

Students are tasked with solving the following problems: 1) A runner completes a 400 m lap in 50 seconds. Calculate their average speed. 2) An object falls from rest and accelerates at 9.8 m/s². How far does it fall in 3 seconds? 3) A train travels 300 m in 15 seconds. Determine its average velocity. Students should show all calculations and reasoning.

• m/s
• m/s²
• m/s³
• km/h

Answer: m/s²

Acceleration is defined as the change in velocity per unit time, which is measured in meters per second squared (m/s²).

• Distance
• Speed
• Displacement
• Time

Answer: Displacement

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

Answer: Velocity is the rate of change of displacement and includes direction, while speed is the rate of distance traveled and does not include direction.

Velocity is a vector quantity, meaning it has both magnitude and direction, whereas speed is a scalar quantity.

• It is increasing
• It is decreasing
• It is zero
• It is constant

Answer: It is zero

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

Answer: Average Speed = Total Distance / Total Time

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

• 20 m/s
• 0 m/s
• -20 m/s
• 10 m/s

Answer: 0 m/s

At the peak of its motion, the object's velocity is zero before it starts descending.

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

In uniform acceleration, the object experiences the same increase in velocity during equal time intervals.