Kinematics

1 / 2

Sign = Direction, Not Just Size

v = \frac{ds}{dt}, \quad a = \frac{dv}{dt}

Distance/speed ignore sign; displacement/velocity keep it as direction. Same signs of $v,a$ → speeding up; opposite → slowing down. Reflex: Read the sign as the side/direction first.

swipe up ↑

🤖Ask

Kinematics

2 worked examples

Sign = Direction, Not Just Size

v = \frac{ds}{dt}, \quad a = \frac{dv}{dt}

Distance/speed ignore sign; displacement/velocity keep it as direction. Same signs of $v,a$ → speeding up; opposite → slowing down. Reflex: Read the sign as the side/direction first.

v=0 Rest, a=0 Extreme Velocity

s \to v \to a

$v=0$ : instant rest, usually a turning point. $a=0$ : max/min velocity. Distance = area under $v$ – $t$ graph. Reflex: Rest ⇒ v=0; extreme velocity ⇒ a=0; fix constants from initial conditions.

↩ Back to Kinematics