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Questions and Answers
What is the definition of speed?
What is the definition of speed?
Speed is a measure of how fast an object is moving.
How can average speed be calculated?
How can average speed be calculated?
Average speed can be calculated by dividing distance by time.
Define velocity.
Define velocity.
Velocity is the displacement per unit of time.
What is acceleration?
What is acceleration?
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Acceleration can be calculated using the formula change in velocity divided by ____. (Fill in the blank)
Acceleration can be calculated using the formula change in velocity divided by ____. (Fill in the blank)
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What does Newton's First Law of Motion define?
What does Newton's First Law of Motion define?
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Newton's Second Law states that force is equal to mass multiplied by acceleration.
Newton's Second Law states that force is equal to mass multiplied by acceleration.
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Study Notes
Physics: Speed, Velocity, and Acceleration
- Speed: a measure of how fast an object is moving; can be calculated using the formula: Speed = Distance / Time
- Units: important in speed calculations (e.g., meters per second, kilometers per hour)
- Example: a train moves at a constant speed of 90 km/h; how far does it travel in 4 hours? (Answer: 360 km)
Velocity
- Definition: displacement per unit of time; includes direction
- Formula: Velocity = Displacement / Time
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Examples:
- A bird flies 150 meters east in 5 seconds; what is its velocity? (Answer: 30 m/s east)
- A swimmer swims 200 meters east in 40 seconds; what is her velocity? (Answer: 5 m/s east)
Acceleration
- Definition: rate at which velocity changes over time; can be positive (speeding up) or negative (slowing down)
- Formula: Acceleration = Change in Velocity / Time
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Examples:
- A plane decelerates from 200 m/s to 100 m/s in 10 seconds; what is its acceleration? (Answer: -10 m/s²)
- A car increases its velocity from 20 m/s to 50 m/s in 10 seconds; what is its acceleration? (Answer: 3 m/s²)
Newton's Laws of Motion
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Newton's First Law of Motion: inertia; an object at rest will stay at rest, and an object in motion will stay in motion with the same speed and direction, unless acted upon by an external force
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Examples: a book sliding off a table, a car jerking forward when the brakes are suddenly applied, a ball rolling down a hill, a person sliding on ice, a coin spinning on a table
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Newton's Second Law of Motion: force acting on an object is equal to the mass of the object multiplied by its acceleration; F = ma
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Examples: a 10 kg object is accelerating at 5 m/s²; what is the force acting on it? (Answer: 50 N)
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Newton's Third Law of Motion: for every action, there is an equal and opposite reaction
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Examples: rowing a boat, a balloon rocket, jumping off a diving board
Net Force and Balanced vs Unbalanced Forces
- Net Force: the sum of all forces acting on an object; determines the object's acceleration and overall motion
- Calculating Net Force: add forces if they are in the same direction, subtract forces if they are in opposite directions
- Balanced Forces: when the forces acting on an object are equal in magnitude and opposite in direction; always equal to zero
- Unbalanced Forces: when the forces acting on an object are not equal in magnitude or not opposite in direction
- Example: two forces of 25 N and 25 N acting in opposite directions; the net force is 0 N, indicating balanced forces.
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Description
Learn about the concepts of speed, velocity, and acceleration in physics, and how to calculate them using formulas. Understand the definition of speed and how to calculate average speed.
