Forces

Question 1

Gravity

Answer 1

Fg = mg

Depends on which direction is positive

Question 2

Spring

Answer 2

Fs = -kx

Always acts to reduce extension of spring

Question 3

Friction

Answer 3

Ff = uF

Depends on which direction is positive

Question 4

Buoyancy

Answer 4

Fb = pVg

Question 5

Linear drag

Answer 5

Fd = -cv
Always negative/opposite direction of velocity
Low velocity

Question 6

Quadratic drag

Answer 6

Fd = cv^2
Depends on which direction is positive/ opposite to velocity
High velocity