Net Force

• Define net force and explain how it affects an object's motion.

• Explain the difference between balanced and unbalanced forces.

• Calculate the net force when forces act in the same or opposite directions.

• Predict the direction of motion based on the calculated net force.

Key Vocabulary

Force

A push or a pull that has the ability to change the motion of an object.

Net Force

The total combination of all forces that are acting on a single object at the same time.

Balanced Forces

Equal forces acting on one object in opposite directions, resulting in a net force of zero.

Unbalanced Forces

Unequal forces that cause a change in an object's motion, speed, or its direction.

Friction

A force that works against motion when two surfaces are rubbing or in contact with each other.

Gravity

The fundamental force that pulls all objects on Earth downward toward the center of the planet.

What is Net Force?

• A force is a push or pull on an object, measured in Newtons (N).

• The net force is the overall force found by combining all forces on an object.

• When the net force is not zero, it causes the object to accelerate.

• The object's acceleration is always in the same direction as the net force.

Balanced Forces

• Forces are equal and in opposite directions, making the net force zero.

• They do not cause a change in the object's state of motion.

• A book resting on a table is an example, with its net force being 0 N.

Unbalanced Forces

• Forces are unequal, making the net force greater than zero.

• They cause a change in the object's motion, known as acceleration.

• In tug-of-war, the rope moves in the direction of the larger force.

Same Direction

• ​When multiple forces act on an object in the same direction, you add the forces together.

• ​​The result of adding these forces together is a stronger overall force called the net force.

• ​For example, 25 N + 20 N in the same direction gives a total net force of 45 N.

Opposite Directions

• ​If forces are in opposite directions, you find the net force by subtracting the smaller force from the larger one.

• ​​If unbalanced, the object moves in the direction of the greater force; if balanced, the net force is 0 N.

• ​For example, 12 N to the right and 10 N to the left results in a net force of 2 N right.

• The net force is the sum of all forces acting on an object.

• Balanced forces have a net force of zero and cause no change in motion.

• Unbalanced forces have a net force greater than zero, causing the object to accelerate.

• Add forces in the same direction and subtract them in opposite directions.