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Ch 05: Applying Newton's Laws
Young & Freedman Calc - University Physics 14th Edition
Young & Freedman Calc14th EditionUniversity PhysicsISBN: 9780321973610Not the one you use?Change textbook
Chapter 5, Problem 42b

If the skydiver's daughter, whose mass is 4545 kg, is falling through the air and has the same DD (0.250.25 kg/m) as her father, what is the daughter's terminal speed?

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Identify the forces acting on the skydiver's daughter: The two main forces are gravitational force (weight) and air resistance. At terminal velocity, these forces are balanced, meaning the net force is zero.
Write the equation for terminal velocity: At terminal velocity, the gravitational force (mg) is equal to the drag force (1/2 * D * A * v^2), where m is the mass, g is the acceleration due to gravity, D is the drag coefficient, A is the cross-sectional area, and v is the terminal velocity.
Rearrange the equation to solve for terminal velocity (v): Start with mg = (1/2) * D * A * v^2. Rearrange to isolate v: v = sqrt((2 * m * g) / (D * A)).
Substitute the known values into the equation: Use m = 45 kg, g = 9.8 m/s^2, and D = 0.25 kg/m. Note that the cross-sectional area (A) is not provided in the problem, so you will need to assume it is the same as the father's or use a reasonable estimate.
Simplify the expression to find the terminal velocity: Perform the necessary algebraic operations to compute the terminal velocity, ensuring all units are consistent.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Terminal Velocity

Terminal velocity is the constant speed that a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration. At this point, the force of gravity is balanced by the drag force acting against it, resulting in a net force of zero.
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Drag Coefficient (D)

The drag coefficient (D) is a dimensionless number that quantifies the drag or resistance of an object in a fluid environment, such as air. It depends on the shape of the object and the flow conditions, and it plays a crucial role in determining the drag force experienced by the object as it moves through the fluid.
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Mass and Weight

Mass is a measure of the amount of matter in an object, typically measured in kilograms, while weight is the force exerted by gravity on that mass. Weight can be calculated using the formula W = mg, where W is weight, m is mass, and g is the acceleration due to gravity (approximately 9.81 m/s² on Earth).
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Related Practice
Textbook Question

Two crates connected by a rope lie on a horizontal surface (Fig. E5.375.37). Crate A has mass mAm_A, and crate B has mass mBm_B. The coefficient of kinetic friction between each crate and the surface is μkμ_k. The crates are pulled to the right at constant velocity by a horizontal force FF. Draw one or more free-body diagrams to calculate the following in terms of mAm_A, mBm_B, and μkμ_k: the tension in the rope connecting the blocks.

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Textbook Question

A 5252-kg ice skater spins about a vertical axis through her body with her arms horizontally outstretched; she makes 2.02.0 turns each second. The distance from one hand to the other is 1.501.50 m. Biometric measurements indicate that each hand typically makes up about 1.25%1.25\% of body weight. What horizontal force must her wrist exert on her hand?

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Textbook Question

You throw a baseball straight upward. The drag force is proportional to v2v^2. In terms of gg, what is the y y-component of the ball's acceleration when the ball's speed is half its terminal speed and it is moving back down?

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Textbook Question

A small remote-controlled car with mass 1.601.60 kg moves at a constant speed of v=12.0v = 12.0 m/s in a track formed by a vertical circle inside a hollow metal cylinder that has a radius of 5.005.00 m (Fig. E5.455.45). What is the magnitude of the normal force exerted on the car by the walls of the cylinder at point AA (bottom of the track)?

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Textbook Question

A small remote-controlled car with mass 1.601.60 kg moves at a constant speed of v=12.0v = 12.0 m/s in a track formed by a vertical circle inside a hollow metal cylinder that has a radius of 5.005.00 m (Fig. E5.455.45). What is the magnitude of the normal force exerted on the car by the walls of the cylinder at point BB (top of the track)?

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Textbook Question

You throw a baseball straight upward. The drag force is proportional to v2v^2. In terms of gg, what is the y y-component of the ball's acceleration when the ball's speed is half its terminal speed and it is moving up?

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