Box in a Truck Bed 2#
A semi-truck is approaching a stop-light as it drives down the road moving in the negative direction. There is a box in the back of the semi-truck which, according to the driver, stays IN PLACE the whole time until the semi-truck has come to a complete stop.
What type of friction is acting the box? From the perspective of a pedestrian watching the semi-truck drive past, is the work by the friction force on the box positive, negative, or zero?
Kinetic friction, positive work
Kinetic friction, negative work
Kinetic friction, zero work
Static friction, positive work
Static friction, negative work
Static friction, zero work