PX155 - A2 - newton's second law

basis:
- mass is a property that "resists" acceleration (mass measures "inertia")
- define momentum $p = m v$
"the rate of change of momentum of a body is equal to the total external force acting upon it"
or
"force equals rate of change of momentum"

F = \frac{d p}{d t}

if mass ( $m$ ) is constant (can be approximated as such)

F = m \frac{d v}{d t} = m a

example 1.1:
an oil tanker with mass(m) = $500, 000 t$
engine is the propeller exerting a force(F) = $5 \times 10^{6} N$
how long does it take to reach $5 m s^{- 1}$ from rest?
$a = \frac{F}{m} = \frac{5 \times 10^{6}}{5 \times 10^{8}} = 10^{- 2} m s^{- 1}$
v=u+at
$5 = 0 + 10^{- 2} t$
$∴ t = 500 s$