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Ch 13: Newton's Theory of Gravity
Knight Calc - Physics for Scientists and Engineers 5th Edition
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Non è quello che usi tu?Cambia libro di testo
Capitolo 13, Problema 36

What is the net gravitational force on the 20.0 kg mass in FIGURE P13.36? Give your answer using unit vectors.

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Identify the masses involved in the problem and their positions relative to the 20.0 kg mass. Use the diagram in FIGURE P13.36 to determine the distances and angles between the masses.
Recall Newton's law of gravitation: F=Gmm1r2, where G is the gravitational constant, m and m1 are the masses, and r is the distance between them. Calculate the gravitational force exerted by each mass on the 20.0 kg mass.
Break each gravitational force into its components along the x- and y-axes using trigonometry. For example, the x-component of a force is Fx=F⁢cos⁢θ, and the y-component is Fy=F⁢sin⁢θ, where θ is the angle of the force vector.
Sum the x-components of all the forces to find the net force in the x-direction, and sum the y-components to find the net force in the y-direction. Use vector addition to combine these components into a single net force vector.
Express the net gravitational force on the 20.0 kg mass in unit vector notation, F=Fxi+Fyj, where i and j are the unit vectors in the x- and y-directions, respectively.

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Gravitational Force

Gravitational force is the attractive force between two masses, described by Newton's law of universal gravitation. It is directly proportional to the product of the masses and inversely proportional to the square of the distance between their centers. The formula is F = G(m1*m2)/r^2, where G is the gravitational constant. This force acts downward towards the center of the Earth or any other massive body.
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Unit Vectors

Unit vectors are vectors with a magnitude of one, used to indicate direction. In physics, they are often represented as i, j, and k for the x, y, and z axes, respectively. When calculating forces, expressing them in terms of unit vectors allows for easier addition and subtraction of vector quantities, as well as clearer representation of direction in a coordinate system.
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Net Force

The net force is the vector sum of all individual forces acting on an object. It determines the object's acceleration according to Newton's second law, F_net = m*a. In the context of gravitational forces, the net gravitational force on an object is found by adding the gravitational forces exerted by other masses, taking into account their directions and magnitudes, often expressed in unit vector form.
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Finding Net Forces in 2D Gravitation