Questions and Answers
What is the average speed of the bus that decreases its speed from 80 km/h to 60 km/h over 5 seconds?
What type of motion is described when a train starts from rest and accelerates uniformly to a speed of 40 km/h?
Which statement correctly describes uniform acceleration?
In the context of the speed of the bus, which of the following describes a non-uniform acceleration?
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How can a straight line graph of distance versus time represent uniform speed?
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When a cyclist initially at rest accelerates uniformly, which of the following measures is critical in determining its acceleration?
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If a graph shows distance versus time for a moving object, what does a horizontal line indicate?
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What example illustrates non-uniform acceleration?
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Which of the following statements correctly defines uniform motion?
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In the case of Rahul paddling his bicycle and achieving uniform acceleration, which aspect is key in identifying this motion?
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Study Notes
Acceleration and Motion
- Acceleration is defined as the change in velocity per unit time.
- Uniform acceleration indicates a constant change in velocity over time.
- Non-uniform acceleration occurs when the rate of change of velocity varies.
- The SI unit for acceleration is meters per second squared (m s²).
Key Equations of Motion
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First Equation: v = u + at, where:
- v = final velocity
- u = initial velocity
- a = acceleration
- t = time
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Second Equation: s = ut + ½ at², where:
- s = distance traveled
- Third Equation: 2as = v² – u², relating acceleration and velocity.
Types of Motion
- Uniform Circular Motion: Occurs when an object moves in a circular path at a constant speed.
- An athlete completing a circular path of diameter 200 m in 40 s experiences uniform circular motion.
Average Speed and Velocity
- Average speed is calculated as total distance traveled divided by total time.
- For example, Joseph jogs 300 m in 150 s and returns 100 m in another 60 s; average speeds and velocities can be determined for each leg of his journey.
Acceleration in Everyday Scenarios
- Examples of uniform acceleration include objects falling freely under gravity.
- Example of non-uniform acceleration: a car increasing its speed at varying rates.
Graphical Representation of Motion
- Distance versus time graphs indicate uniform speed with straight lines.
- For uniform motion, the graph shows direct proportionality between distance traveled and time taken.
Example Problems
- A motorboat accelerating at 3.0 m s² for 8.0 s can be used to illustrate distance calculations.
- Understanding acceleration includes distinguishing when it aligns with or opposes velocity direction.
Concept Clarifications
- Acceleration is considered positive when in the direction of motion, and negative when opposing it.
- Exercises include practical applications, like calculating average speed from various distances and time intervals.
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Description
This quiz covers the concept of acceleration, including its definition as the change in velocity per unit time. It also explores uniform and non-uniform motion through graphical representation and discusses the key equations of motion for objects under uniform acceleration.
