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Questions and Answers
What is the approximate acceleration of an object falling freely near the Earth's surface?
What is the approximate acceleration of an object falling freely near the Earth's surface?
- $19.6 \ m/s^2$
- $4.9 \ m/s^2$
- $29.4 \ m/s^2$
- $9.8 \ m/s^2$ (correct)
What is terminal velocity?
What is terminal velocity?
- The average speed of a falling object
- The maximum speed of an object when the forces are balanced (correct)
- The speed of an object right before impact
- The initial speed of a falling object
When an object reaches terminal velocity, what is the resultant force acting on it?
When an object reaches terminal velocity, what is the resultant force acting on it?
- Minimum
- Zero (correct)
- Maximum
- Equal to its weight
What happens to the speed of a skydiver when their parachute opens?
What happens to the speed of a skydiver when their parachute opens?
What causes a skydiver to slow down after opening their parachute?
What causes a skydiver to slow down after opening their parachute?
What force initially causes an object to accelerate when falling through a fluid?
What force initially causes an object to accelerate when falling through a fluid?
As an object falls through a fluid and its speed increases, what happens to the frictional force acting on it?
As an object falls through a fluid and its speed increases, what happens to the frictional force acting on it?
What happens to an object's acceleration as it falls through a fluid before reaching terminal velocity?
What happens to an object's acceleration as it falls through a fluid before reaching terminal velocity?
When does an object stop accelerating during free fall?
When does an object stop accelerating during free fall?
What remains constant for a falling object, assuming it stays whole?
What remains constant for a falling object, assuming it stays whole?
Flashcards
Free-fall acceleration
Free-fall acceleration
The acceleration of an object falling freely near the Earth's surface, approximately 9.8 m/s².
Terminal velocity
Terminal velocity
The maximum constant speed reached by an object falling through a fluid, when the force of gravity equals the fluid resistance.
Resultant force
Resultant force
The single force that results from combining all forces acting on an object. At terminal velocity this force is zero.
Initial fall stage
Initial fall stage
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Acceleration decreasing
Acceleration decreasing
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Constant speed stage
Constant speed stage
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Parachute opens
Parachute opens
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New terminal velocity
New terminal velocity
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Study Notes
- Objects falling freely near the Earth's surface accelerate at approximately 9.8 m/s².
- Objects falling through fluids eventually reach terminal velocity.
- At terminal velocity, an object maintains a constant speed and direction due to a zero resultant force.
- A skydiver falling spread-eagled reaches a terminal velocity of about 53 m/s.
Stages of Falling Through a Fluid
- The weight of a falling object remains constant, assuming it stays intact.
- Initially, an object accelerates due to gravity, its speed increases.
- The resultant force acts downwards as the frictional force is less than the object's weight.
- As speed increases, the frictional force also increases, but remains less than the weight, so acceleration decreases.
- Terminal velocity is reached when the frictional force equals the weight, resulting in zero resultant force and constant speed.
- Opening a parachute increases air resistance causing the skydiver to slow down.
- A new, lower terminal velocity is achieved after the parachute opens.
- The illusion of a skydiver moving upwards when the parachute opens is due to the camera operator opening their parachute later and falling past the skydiver.
- An object continues to fall at terminal velocity unless it hits the ground, even when the resultant force is zero.
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