Universal Gravitation Law

Every two objects with mass have a(n) ___ force attracting them together.

• gravitation

• electrical

• spring

• friction

According to Newton's 3rd Motion Law, the force of the earth on the apple ___ the force of the apple on the earth.

• >

• <

• =

• ≥

The Universal Gravitation Law is true ___.

• everywhere

• only on earth

• only in our solar system

• only in the Milky Way Galaxy

The Universal Law of Gravitation says the gravity attractive force between any two masses (m₁ and m₂) separated by a distance r (center to center) is ___.

• Gm₁m₂/r²

• km₁/r

• (m₁ + m₂)r

• (m₁ + m₂)/r

In Newton's Universal Law of Gravitation (F_g = Gm₁m₂/r²), the Universal Gravitation Constant G = ___.

• ~6.67 × 10^-11 N•m²/kg²

• ~9.81 m/s²

• ~3.141593

• ~2.718281828

Cavendish measured the Universal Gravitation Constant G with two masses turning from a hanging wire toward two other masses. Then by using the Universal Law of Gravitation, he could calculate ___.

• the earth's mass

• the first two masses

• the second two masses

• his mass

The average distance between the earth and the sun, center to center, is ___ .

• 1 astronomical unit (AU)

• 80 million miles

• 100 million km

• 5 light-minutes

We would not be here if our solar system's planets did not have very circular orbits, but technically, they have ___ shaped orbits.

• ellipse

• square

• triangle

• helical

An object's orbital period is how long it takes to orbit once around another object. What is the orbital period of the earth around the sun?

• 1 year

• 1 month

• 1 decade

• 1 day

If you move from far out in space to one-fourth of your distance from earth's center, then your weight will ___.

• increase

• decrease

• stay the same

• disappear