Force is defined as a push or pull that can cause an object's motion to change. It is measured in Newtons (N), with 1N being the force needed to accelerate 1kg of mass by 1m/s^2. There are two main types of forces - contact forces like friction and tension which require touching objects, and action-at-a-distance forces like gravity and magnetism which act without direct contact. Force is a vector quantity that has both magnitude and direction.

3. 2. buoyant force (buoyancy)- it is the upward force of fluids on floating objects. 3. normal force- is the support force on an object which is in contact with another stable object. 4. air resistance force - type of frictional force upon objects as they travel through the air.