A crew member is walking on a tugboat that is pulling a barge. The tugboat is moving at a constant speed upstream in a river that has a constant downstream current. In the situation above, what is at rest relative to the tugboat?

co2reflects heat radiation back to earth buning coal and oil emits co2 globe warms

measure their densities same density, same sub

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement