Answer
(a) The magnitude of the propelling force is $1098N$
(b) The magnitude of the net force is $648N$
Work Step by Step
- The forces resisting the motion, we would call them all $R=450N$
- The force propelling the bobsled forward, we call it $P$
As these two forces are opposite in direction, we have $$\sum F=P-R$$
(a) Because the bobsled has acceleration $a=2.4m/s^2$, we have the equation $$P-R=(M_{bobsled+riders})a=270\times2.4=648N$$ $$P=648+R=1098N$$
(b) The magnitude of the net force is $$\sum F=P-R=1098-450=648N$$
