What is the formula of NET FORCE?

Question

Please help me on this...,

Here's the question...

Together a motorbike and rider have a mass of 275 kg. the rider slows the motorbike at -4.50m/s2. What is the net force on the motorbike?

What does the negative sign signify???

Oh please help me on this...

Answer 1

The neg. sign means the acceleration is in a direction opposite to the motion, i.e., the bike slows down rather than speeds up.

Since a=-4.50 and m=275, F=ma=(275)(-4.50)=1237.5 N