Space

Question 1

What do the variables (and what are their units) in Newton’s universal gravitational formula.

F = G m_Em_O

   r<sup>2</sup>

Answer 1

G = gravitational constant  (6.672x10^-11)
m<sub>e</sub>= mass of the earth (kg)
m<sub>o</sub>= mass of the object (kg)
r = radius of the earth in **_metres_**

Question 2

Derive a formula for gravity by combining Universal Gravitional law with Newtons second law which assumes acceleration is g

Answer 2

1. F=mg
2. F = G m_em_o

                                                   r<sup>2</sup>

Answer g = Gm_o

                 r<sup>2</sup>

Question 3

How does altitude effect gravity formula?

Answer 3

we already know that with altitude gravity decreases.

g = Gm_o

     (r+alt)<sup>2</sup>

Make sure radius and alt are in meters

Question 4

What is the difference between G and g?

Answer 4

G= gravitational constant which is found on data sheet.

g= acceleration due to gravity which is 9.8ms^-2 on earth.

Question 5

What is the difference between weight and mass?

Answer 5

Mass is measured in Kg and is the same throughout the universe.

Weight is a force of your mass due to gravity and is measured in Newtons.

W =mg

Question 6

What happens if an object is moved to a higher altitude within a gravitational field?

Answer 6

It’s E_p increases so work has to be done on the object by an external force (rockets)

Question 7

What happens to an object if it is moved to a lower altitude?

Answer 7

Its E_p decreases so work is done on the object by gravity.