Forces can cause objects to be in motion, change motion, or remain at rest. A force is a push or pull that acts on an object. Forces have magnitude, direction, point of application, and line of action. Balanced forces cause no change in motion, while unbalanced forces cause a change in motion. Common forces include tension, normal force, gravity, friction. An activity is described where students observe and analyze forces on objects at rest like a hanging pen or book being pushed.