Lucy boards a crowded bus as it sits in the station. There are no available seats, so Lucy stands in the center aisle next to a support pole. As the bus starts moving forward and picks up speed, Lucy holds the pole tightly to avoid falling over backward. While the bus is speeding up, what is the direction of the total force (if any) on Lucy?

Is it forward? baclwards? or the total force is zero?

As the bus drives down a straight road at a constant speed, Lucy has no trouble keeping her balance. During this time, what is the direction of the total force (if any) on Lucy?

Is it forward? baclwards? or the total force is zero?

The bus comes to a sudden stop at a red light, and Lucy grips the pole tightly to avoid falling over forward. During this time, what is the direction of the total force (if any) on Lucy?

Is it forward? baclwards? or the total force is zero?