The Earth may be assumed to be spherical with radius r and density p.

Which equation correctly relates the gravitational field strength g at its surface to these quantities and

the gravitational constant G?

• g=G/ r²

• g=3 G \ 4 π r p

• g= G 4 π r p \ 3

• g= G 4 π r² p \ 3

The gravitational field strength outside a uniform sphere of mass Mis the same as that of a point mass Mat the centre of the sphere. The Earth, which may be assumed to be spherical and of radius r, has a gravitational field strength g at its surface. Which expression gives the gravitational field strength at height h above the ground?

• g r² / (r + h)²

• g r / r + h

• g (r- h) / r

• g (r-h)² / r²

Two isolated masses m₁ and m₂ are separated by a distance r. Which expression gives the gravitational field strength caused by m₁ at m₂?

• G m1m2 / r

• G m1 m2 / r²

• G m1 / r²

• G m2 / r²

Tags

NGSS.HS-PS2-4

What is numerically equal to the gravitational field strength at a point P on the Earth's surface?

• the acceleration of free fall at P.

• the change in potential energy per unit distance from P.

• the force acting on any body placed at P.

• the work done in bringing unit mass from infinity to P.

Tags

NGSS.HS-PS2-4

The acceleration of free fall on the Earth's surface may be taken to be 6 times the value on the Moon's surface. The mean density of the Earth may be taken to be 5/3 times the value of the Moon. The radius of the Earth is r_E and that of the Moon is r_M. What is the ratio r_E / r_M ?

• 1.9

• 3.6

• 6

• 10

Which statement about a uniform gravitational field is true?

• Its magnitude is the same in all directions.

• The gravitational potential has the same value at all points within it.

• Its direction is opposite to the direction of motion of a test mass released in it.

• Its field strength is the same at all points within it.

A body of mass 20 kg mass is placed 4 m

above the Earth's surface. The value of g

may be taken as lOms^-2 . What are the gravitational field strength and gravitational force acting on the body?

• A

• B

• C

• D

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-4

A mass m is released just above the surface of a planet with mass M and radius R . Which expression gives its initial gravitational acceleration?

• GmM / R

• GmM / R³

• G M / R²

• GmM / 2 R

The Earth may be assumed to be spherical with mass M and radius R, with acceleration of free fall g at its surface. Which equation correctly shows how the these quantities?

• G = g M / R²

• G = R² / g M

• G = R² M / g

• G = M / g R²

At the Earth's surface, the gravitational field strength is about lO N kg^-1. At a point outside the Earth and a distance x from its centre, the field strength is about 5 N kg^-1. Which expression gives an approximate value for the radius of the Earth?

• x/5

• x / 2 √2

• x / 2

• x / √2