Newton's Laws & Forces

Question 1

What is Newton’s First Law?

Answer 1

Every body continues in its state of rest or uniform motion unless acted on by an external force.

Question 2

What is Newton’s Second Law?

Answer 2

The rate of change of momentum of a body is equal to the total external force acting upon it. (F = ma)

Question 3

What is Newton’s Third Law?

Answer 3

To every action there is an equal and opposite reaction.

Question 4

What are the two contact forces on a macroscopic level?

Answer 4

Normal reaction and frictional forces.

Question 5

How do you work out the maximum static friction of an object?

Answer 5

max(FS) = µS*N

where µS is the coefficient of static friction.

Question 6

How do you work out the maximum kinetic friction of an object?

Answer 6

FK = µK*N

where µK is the coefficient of kinetic friction.

Question 7

What is the equation for gravitational force between two point masses?

Answer 7

F(1-2) = -(GMm)/(r^2) r(hat)

Question 8

What is the magnitude of the gravitational constant G?

Answer 8

6.67*10^-11 N m^2 kg^-2

Question 9

How would you calculate the force on one sphere due to 2 other spheres if they are all in contact?

Answer 9

Calculate the force due to one sphere and then use the centre of mass of this sphere and the other sphere (using cos(theta) etc)

Question 10

What is the equation for the mass of a sphere including its density?

Answer 10

4/3 * pi * r^3 * ϱ, where ϱis the density.