M5.4 Gravitational fields

Question 1

how to draw gravitational field lines near the surface

Answer 1

parallel to each other
more lines - stronger field

Question 2

define force field

Answer 2

any region of space where an object experiences force

Question 3

define newtons law fo gravitation

Answer 3

force is proportional to the product of two objects masses and inversly proportional to their distance

Question 4

how is force affected by a change in the radius of orbit

Answer 4

F proportional to distance squared
inverse square law because think fthe field like sphere

Question 5

why is their no second mass in the equation for g

Answer 5

because in F = ma g is the acceleration
the objects mass is irrelevant
basketball and cannon ball fall at the same rate

Question 6

What is Kepler’s first law

Answer 6

orbit of a planet is an ellipse

Question 7

what is Keplers second law

Answer 7

the same area of the ellipse is travelled in a set amount of time

Question 8

what is Keplers third Law

Answer 8

Square of the period is proportional to the square of the radius

Question 9

why is GPE on surface 0

Answer 9

when close to the surface when using Mgh the value found is the difference in GPE

Question 10

Why is GPE negative [2]

exam question

Answer 10

G force is attractive / work is required to move away from the earth

and Vg is set to 0 at infinity so is negative nearer the earths surface