A.
Let's assume the bus will take 6 seconds to go from rest to 20 mph.
1.
To convert from mph to m/s, we need to multiply our value by 0.44, so we have:
[tex]20\cdot0.44=8.8\text{ m/s}[/tex]
2.
To find the acceleration of the bus, let's divide the change in velocity by the amount of time:
[tex]a=\frac{\Delta V}{\Delta t}=\frac{8.8}{6}=1.47\text{ m/s^^b2}[/tex]
3.
Using the second law with a mass of 70 kg, let's calculate the force:
[tex]\begin{gathered} F=m\cdot a\\ \\ F=70\cdot1.47=102.9\text{ N} \end{gathered}[/tex]
4.
The weight force is given by:
[tex]F_W=m\cdot g=70\cdot9.8=686\text{ N}[/tex]
Therefore this force is less than the gravitational force.
5.
The force factor is:
[tex]F=\frac{102.9}{686}=0.15[/tex]
