Chapter 11

Question 1

What is Newton’s first law of motion?

Answer 1

Any object remains in a state of uniform motion unless a resultant external force acts on it

Question 2

What is Newton’s second law of motion?

Answer 2

The acceleration of an object is proportional to the resultant force upon it. Force is proportional to the rate of change of momentum.

Question 3

What is Newton’s third law of motion?

Answer 3

If body A exerts a force on body B, then body B exerts a force of the same magnitude but the opposite direction and the same type on body A

Question 4

How do you calculate momentum?

Answer 4

p=m*v units are kg m s^-1

Question 5

What are the 2 most important things to remember about momentum?

Answer 5

It is conserved in a closed system

It is a vector quantity

Question 6

How do you calculate the change in momentum?

Answer 6

Final momentum - Initial momentum

Question 7

What is impulse?

Answer 7

The change in momentum

Question 8

What are the 2 equations for calculating impulse?

Answer 8

Final momentum - initial momentum

Average force * time applied for

Question 9

What are the 3 categories of collisions, and how do they differ?

Answer 9

1) they coalesce: totally inelastic collision
2) Elastic collision: kinetic energy is conserved
3) Inelastic collision: some kinetic energy is lost, but they do ‘bounce’

Question 10

What is the full equation associated with Newton’s second law of motion?

Answer 10

F=m(dv/dt) + v(dm/dt)

But dm/dt is nearly always 0, so can be simplified to F=ma in most cases

Question 11

What is Kepler’s first law?

Answer 11

A planet moves in an ellipse with the Sun at one focus

Question 12

What is Kepler’s second law?

Answer 12

The line from the Sun to a planet sweeps out equal areas in equal times

Question 13

What is Kepler’s third law?

Answer 13

Square of orbital time is proportional to cube of orbital radius

Question 14

How do you calculate acceleration towards the centre of a circle?

Answer 14

a=v^2/r

Question 15

How do you calculate centripetal force?

Answer 15

F=mv^2/r =m(omega)^2 r

Question 16

What is the equation for gravitational attraction?

Answer 16

F=-Gm(1)m(2)/r^2

Question 17

How do you calculate gravitational field strength?

Answer 17

g=-GM/r^2

Question 18

What is gravitational potential?

Answer 18

g(delta)h. The difference in gravitational potential energy per kilogram of material

Question 19

How do you calculate gravitational potential?

Answer 19

V(grav)=constant-1/2 v^2=GM/R

Question 20

What is an escape velocity?

Answer 20

To get out of a gravitational well (have a negative potential energy), need to have enough kinetic energy to make total energy greater than 0. If know gravitational potential energy, can calculate required escape velocity