Force A push or pull on an object. For example, gravity is the force that pulls objects towards Earth's center. When an object is at rest, any force acting on it is balanced by an equal force in the opposite direction. If a new, unbalanced force acts on the object, the object will move in the same direction as the new force. Imagine a house being pulled toward Earth's center by gravity, while the ground is pushing back up on the house. If the forces are equal (the house is on solid ground), the house doesn't move. If the forces are unbalanced (the ground is soft and muddy and pushes back with less force), then the house sinks down into the ground. If a new force, such as a bulldozer, acts on the house without a balancing force in the opposite direction, the house will move in the direction the bulldozer is pushing.