A Summary of Linear Motion

Being to the left of the origin means…

x(t) is negative

Being to the right of the origin means…

x(t) is positive

Moving left means…

x’(t) is negative

Moving right means…

x’(t) is positive

Moving away from the origin means…

x(t) and x’(t) have the same sign

Moving towards from the origin means…

x(t) and x’(t) have opposite signs

Velocity increasing means…

x’’(t) is positive

Velocity decreasing means…

x’’(t) is negative

Speeding up means…

x’(t) and x’’(t) have the same sign

Slowing down means…

x’(t) and x’’(t) have opposite signs