Earth's average radius is \(6,370 \mathrm{km}\) and its mass is \(5.97 \times 10^{24} \mathrm{kg}\) Show that the acceleration of gravity at the surface of Earth is \(9.81 \mathrm{m} / \mathrm{s}^{2}\).

Short Answer

Expert verified
Gravitational acceleration at Earth's surface is about 9.81 \( \mathrm{m} / \mathrm{s}^2 \).

Step by step solution

01

Identify the formula for gravitational acceleration

Use the formula for gravitational acceleration: \( g = \frac{G M}{R^2} \) where \( G \) is the gravitational constant, \( M \) is the mass of the Earth, and \( R \) is the radius of the Earth.
02

Substitute the known values

Substitute the values: \( G = 6.674 \times 10^{-11} \mathrm{m}^3 \mathrm{kg}^{-1} \mathrm{s}^{-2} \), \( M = 5.97 \times 10^{24} \mathrm{kg} \), and \( R = 6,370 \times 10^3 \mathrm{m} \).
03

Perform the calculation

Calculate the gravitational acceleration:\[ g = \frac{6.674 \times 10^{-11} \times 5.97 \times 10^{24}}{(6.370 \times 10^6)^2} \] Simplify the expression to get \[ g \approx 9.81 \mathrm{m} / \mathrm{s}^2 \].

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Earth's Mass
Earth's mass is a crucial component when calculating the gravitational acceleration at the surface of the Earth. The mass of the Earth is a staggering value of \(5.97 \times 10^{24} \mathrm{kg}\). This massive amount of matter contributes to the gravitational pull we experience on the surface.

Understanding this value helps explain why gravity is strong enough to hold the atmosphere in place and keep us grounded. It is this immense mass that generates the gravitational force according to Newton's law of universal gravitation.
Earth's Radius
The Earth's radius is another essential factor in determining the gravitational acceleration. The average radius of the Earth is \(6,370 \mathrm{km}\), which converts to \(6.37 \times 10^6 \mathrm{m}\).

This radius is vital because gravitational force decreases with the square of the distance from the object's center of mass. By using the Earth's radius in our calculations, we can determine the gravitational acceleration on the surface.

The greater the radius, the smaller the gravitational pull at the surface, assuming the mass stays constant. This is inversely proportional to the square of the radius (\( R^2 \)) in the gravitational acceleration formula.
Gravitational Constant
The gravitational constant, denoted as \(G\), is a fundamental value in physics that appears in the equation for gravitational force. The value of \(G\) is \(6.674 \times 10^{-11} \mathrm{m}^3 \mathrm{kg}^{-1} \mathrm{s}^{-2}\). This constant allows us to relate the gravitational force to the masses involved and the distance between them.

Incorporating \(G\) in calculations with Earth's mass and radius lets us derive the gravitational acceleration at the Earth's surface. The formula used is \[ g = \frac{G M}{R^2} \].

By substituting Earth's mass and radius into this equation, and applying the gravitational constant \(G\), we can accurately compute the acceleration due to gravity as \(9.81 \mathrm{m} / \mathrm{s}^2 \). This acceleration is constant and plays a fundamental role in everyday life, from falling objects to the mechanics of orbital satellites.

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Most popular questions from this chapter

Go to NASA's "Apollo 15 Hammer-Feather Drop" Web page (http://nssdc.gsfc.nasa.gov/planetary/lunar/apollo_15_feather_ drop.html) and watch the video from Apollo 15 of astronaut David Scott dropping the hammer and falcon feather on the Moon. (You might find a better version on YouTube.) What did this experiment show? What would happen if you tried this on Earth with a feather and a hammer? Would it work? Suppose instead you dropped the hammer and a big nail. How would they fall? How does the acceleration of falling objects on the Moon compare to the acceleration of falling objects on Earth?

If the Moon had twice the mass that it does, how would the strength of lunar tides change? a. The highs would be higher, and the lows would be lower. b. Both the highs and the lows would be higher. c. The highs would be lower, and the lows would be higher. d. Nothing would change.

Explain the difference between circular velocity and escape velocity. Which of these must be larger? Why?

Rank the following objects in order of their circular velocities, from smallest to largest. a. a 5 -kg object orbiting Earth halfway to the Moon b. a 10 -kg object orbiting Earth just above Earth's surface c. a 15 -kg object orbiting Earth at the same distance as the Moon d. a \(20-\mathrm{kg}\) object orbiting Earth one-quarter of the way to the Moon

What is the advantage of launching satellites from spaceports located near the equator? Would you expect satellites to be launched to the east or to the west? Why?

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