What is the ratio of the sun's gravitational force on you to the earth's gravitational force on you?
Ch 13: Newton's Theory of Gravity
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Not the one you use?Change textbook
Chapter 13, Problem 5
What is the force of attraction between a 50 kg woman and a 70 kg man sitting 1.0 m apart?
Verified step by step guidance1
Step 1: Identify the formula for gravitational force. The force of attraction between two masses is given by Newton's law of universal gravitation: , where is the gravitational constant, and are the masses, and is the distance between them.
Step 2: Substitute the known values into the formula. The gravitational constant is approximately . The masses are kg and kg, and the distance is m.
Step 3: Plug the values into the formula: . This step involves substituting the values for , , , and into the equation.
Step 4: Simplify the numerator. Multiply by and to calculate the product in the numerator.
Step 5: Divide the result by the square of the distance. Since , the square of the distance is . Perform the division to find the force of attraction.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Newton's Law of Universal Gravitation
Newton's Law of Universal Gravitation states that every point mass attracts every other point mass in the universe with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. This law can be mathematically expressed as F = G(m1*m2)/r^2, where F is the gravitational force, G is the gravitational constant, m1 and m2 are the masses, and r is the distance between them.
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Gravitational Constant
The gravitational constant, denoted as G, is a fundamental physical constant used in the calculation of gravitational forces between two objects. Its approximate value is 6.674 × 10^-11 N(m/kg)^2. This constant is crucial for quantifying the strength of the gravitational attraction in Newton's Law of Universal Gravitation, allowing us to calculate the force between two masses at a given distance.
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Mass and Weight
Mass is a measure of the amount of matter in an object, typically measured in kilograms (kg), 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). Understanding the distinction between mass and weight is essential for applying gravitational concepts correctly.
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