Physics - Term 1 - Week 5

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. Velocity is defined as the rate of change of displacement, while speed is the rate of change of distance. Understanding these concepts is crucial for analyzing motion.

For uniformly accelerated motion, we can use the following equations: 1. v = u + at 2. s = ut + 0.5at² 3. v² = u² + 2as Where 'u' is the initial velocity, 'v' is the final velocity, 'a' is the acceleration, 't' is the time, and 's' is the displacement. These equations allow us to solve various problems related to motion.

A car accelerates from rest at a rate of 2 m/s² for 5 seconds. To find the displacement, we can use the equation s = ut + 0.5at². Here, u = 0, a = 2 m/s², and t = 5 s. Plugging in the values, we get s = 0 + 0.5(2)(5²) = 25 m. Thus, the car travels 25 meters during this time.

A cyclist moving at a speed of 10 m/s accelerates at 1 m/s² for 4 seconds. To find the final velocity, we use v = u + at. Here, u = 10 m/s, a = 1 m/s², and t = 4 s. Therefore, v = 10 + (1)(4) = 14 m/s. The final velocity of the cyclist is 14 m/s.

Consider a ball thrown upwards with an initial velocity of 20 m/s. Calculate the time taken to reach the highest point and the maximum height reached. Use the equation v = u + at, where at the highest point, v = 0 m/s. Rearranging gives t = (v - u) / a = (0 - 20) / (-9.8) ≈ 2.04 seconds. For maximum height, use s = ut + 0.5at². Substitute u = 20 m/s, t = 2.04 s, and a = -9.8 m/s² to find s.

Solve the following problems: 1) A car accelerates from 15 m/s to 25 m/s in 5 seconds. Calculate the acceleration. 2) A runner covers a distance of 100 m in 10 seconds. What is their average speed? 3) An object falls freely from rest for 3 seconds. Calculate the distance fallen. Use the equations of motion discussed in class.

• m/s
• m/s²
• km/h
• m

Answer: m/s²

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

• 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, which implies that the acceleration is zero.

• s = ut + 0.5at²
• v = u + at
• v² = u² + 2as
• s = vt

Answer: v = u + at

The equation v = u + at directly relates final velocity to initial velocity, acceleration, and time.

Answer: Displacement is the shortest distance from the initial to the final position of an object, while distance is the total path length traveled.

Displacement is a vector quantity, having both magnitude and direction, whereas distance is a scalar quantity.

• Distance over time
• Acceleration over time
• Velocity over time
• Displacement over time

Answer: Velocity over time

A velocity-time graph shows how the velocity of an object changes over time.

Answer: 78.4 meters

Using the equation s = 0.5gt², where g = 9.8 m/s², we find s = 0.5 * 9.8 * (4)² = 78.4 m.

• 20 m/s
• 25 m/s