Questions and Answers
What is the unit of speed in the SI system?
What is the average speed of an object calculated as?
What is the term used to describe the rate of motion of an object with direction?
What type of motion is described when an object moves along a straight line at a variable speed?
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Which of the following is an example of non-uniform motion?
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What does the odometer of an automobile measure?
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What is the shape of the path of an object in uniform motion?
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If the average speed of an object is 3 m/s and the average velocity is 0 m/s, what can be said about its motion?
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How can the distance of a spaceship from a ground station be calculated if the time taken by a signal to reach the station is known?
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What is the average speed of a car if it travels 400 km in 8 hours?
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Study Notes
Average Speed
- Average speed is calculated by dividing total distance traveled by total time taken.
- Formula: average speed = Total distance traveled / Total time taken
- Example: A car travels 100 km in 2 hours, its average speed is 50 km/h.
Average Velocity
- Average velocity is the arithmetic mean of initial and final velocity for a given period of time.
- Formula: average velocity = (initial velocity + final velocity) / 2
- Example: An object travels 16 m in 4 s and then another 16 m in 2 s, its average speed can be calculated.
Speed and Velocity
- Speed and velocity have the same units (m/s or m s-1).
- Speed only has magnitude, while velocity has both magnitude and direction.
- Velocity can be uniform or variable, and can be changed by changing speed, direction of motion, or both.
Acceleration
- Acceleration is the change in velocity of an object per unit time.
- Formula: acceleration = (change in velocity) / time taken
- Acceleration is a measure of the rate of change of velocity.
Accelerated Motion
- Accelerated motion is a type of motion where velocity changes.
- Example: A bicycle's velocity changes from 0 to 6 m/s in 30 s, and then changes from 6 m/s to 4 m/s in 5 s.
Units of Speed
- SI unit of speed is m/s or m s-1.
- Other units of speed include cm/s and km/h.
Displacement and Distance
- Displacement is the distance measured from the initial to the final position of an object.
- The magnitude of displacement can be equal to the distance travelled by an object, but not always.
Odometer and Distance Travelled
- An odometer is a device that shows the distance travelled by a vehicle.
- The difference between the final and initial readings of an odometer gives the distance travelled.
Speed and Velocity
- Speed is the rate at which an object moves, measured by the distance travelled by the object in unit time.
- The SI unit of speed is metre per second (m s–1).
- Speed can be uniform or variable.
- Velocity is the speed of an object moving in a definite direction, specifying both speed and direction.
- Velocity can be uniform or variable.
Uniform Motion
- In uniform motion, the velocity of an object remains constant with time.
- The path of an object in uniform motion is a straight line.
Non-Uniform Motion
- In non-uniform motion, velocity varies with time.
- The rate of motion of an object can be expressed in terms of average velocity.
Average Speed and Average Velocity
- Average speed is the total distance travelled divided by the total time taken.
- Average velocity is the total displacement divided by the total time taken.
- Average speed and average velocity can be different.
Example Problems
- Calculating average speed and average velocity from given data.
- Finding distance travelled and displacement from odometer readings.
Key Concepts
- Displacement is a vector quantity, while distance is a scalar quantity.
- Speed is a scalar quantity, while velocity is a vector quantity.
- Uniform motion and non-uniform motion have different characteristics.
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Description
Learn about the formulas and calculations of average speed and velocity, with examples and explanations.