The type of force that acts in the opposite direction of an object's motion is called friction.

Here's why:

* Friction is a force that opposes the relative motion of two surfaces in contact.

* When an object moves, friction acts against the direction of its movement, trying to slow it down.

There are different types of friction, including:

* Static friction: The force that prevents an object from starting to move.

* Kinetic friction: The force that acts on a moving object, slowing it down.

Think of pushing a heavy box across a floor. Friction between the box and the floor acts opposite to your pushing force, making it harder to move the box.