CH. 9 physics
What is the magnitude of Earth's gravitational force on a 1-kg body at Earth's surface?
10 N
What is the magnitude of the gravitational force between two 1-kg bodies that are 1 m apart?
6.67 × 10^ -11 N
Earth's gravitational field is strongest at _______.
Earth's surface
What happens to the strength of the gravitational field at the surface of a star that shrinks?
It increases
If Earth shrank, but there was no change in its mass, then what would happen to your weight at the surface?
It would increase.
Would the springs inside a bathroom scale be more compressed or less compressed if you weighed yourself in an elevator that was accelerating upward? Downward?
More compressed while accelerating upward, but less compressed while accelerating downward
Describe how the gravitational forces from the Sun and the Moon compare from one side of Earth to the other.
The Sun exerts a stronger force on the side of Earth nearest the Sun, and the Moon exerts a stronger force on the side nearest the Moon.
What happens to the force of attraction between two planets when the distance between them is doubled?
The force decreases to one quarter.
State Newton's law of universal gravitation in words. Then do the same with one equation.
The force is proportional to the product of two masses and inversely proportional to the square of the distance between their centers: F ~ m1m2/d2.
Which two factors mainly affect ocean tides on Earth?
The sun & the Moon
Would the springs inside a bathroom scale be more compressed or less compressed if you weighed yourself in an elevator that was moving upward at constant velocity? Downward at constant velocity?
There would be no more compression and no more expansion for both upward and downward motion.
Why are occupants of the International Space Station weightless?
They are in free fall.
Do tides depend more on the strength of gravitational pull or on the difference in strengths? Explain.
Tides depend only on the difference.
When G was first measured by Henry Cavendish, newspapers of the time hailed his experiment as the "weighing Earth experiment." Why?
With a known mass, a scale, and the radius of Earth, you can calculate the unknown mass of Earth if you know G.
What would the magnitude of the gravitational field be anywhere inside a hollow, spherical planet?
Zero N/kg
Black holes are essentially _______.
collapsed stars
The constant G in Newton's equation _______.
makes the units of measurement consistent
One's weightlessness in space has most to do with _______.
no support force
What happens to the force of attraction between two planets when the masses of both are doubled?
the force quadruples
What Newton discovered most about gravity is that it is _______.
universal
