Two people push off of each other.
A mother pushes her child on a swing. The mother's push in relation to the mother and the baby is an
Friction (always)
An explosion to the pieces of the bomb afterward.
A mother pushes her child on a swing. The mother's push in relation to just the baby.
The forces in a collision
A person walking in a row boat. The force of the foot on the boat is an
To an object thrown up into the air, gravity is an