Balanced, Unbalanced, and Net Force

5.P.1.4 Predict the Motion of an Object

By Cristine Watkins

​1. Forces occur in pairs and they can be either balanced or unbalanced.

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​Force =

Push or a Pull

2. Balanced forces do not cause change in motion.

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a. This includes if the object is:

i. Not moving

ii. Or moving at a constant speed.

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b. They are equal in size and opposite in direction.

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​Examples of balanced forces in motion and at rest

​Balanced Forces

​Examples of unbalanced forces

​Unbalanced Forces

​3. An unbalanced force always causes a change in motion.

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a. When unbalanced forces act in the same or opposite directions you can find the net force. 

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i. Net force is the overall force acting on an object.

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ii. It is a combination of the magnitude and the direction.​

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iii. ​Magnitude is the difference or the sum between the two forces.

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iv. Direction goes with the stronger force​

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​When forces are unbalanced, the net force > 0

​When forces are balanced the net forces = 0

​Net force is the SUM of all forces acting on an object

balanced forces are equal. unbalanced forces are not equal

100N​

75N​

75N​

75N​

​the Newtons that are going in the SAME DIRECTION

​​Add

​ the Newtons that are going in the OPPOSITE DIRECTION

​

​​Substract

​How to calculate Net Force

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​Remember:

1. Determine the direction and magnitude of each individual force first​

2. when subtracting, subtract the smaller number from the larger number

Multiple Choice

Two teams are playing tug-of-war with a long rope. Both teams have 4 members each that are all about the same size and strength. During the game, 2 members of the same team let go of the rope at the same time and quit playing. Which will most likely occur next?

• The rope will split into two pieces.

• The teams will move towards each other.

• The rope will move in the direction of the team with less members.

• The rope will move in the direction of the team with more members.

Multiple Choice

Which will require the most force to move?

• a 1 kg ball

• a 10 kg ball

• a 100 kg ball

• 1,000 kg ball

Multiple Choice

When two equal and opposite forces are at work, what happens to motion?

• It increases.

• It decreases.

• There is no motion.

• There is maximum friction.

Multiple Choice

Are the forces acting on this object balanced or unbalanced?

• Balanced

• Unbalanced

Multiple Choice

Are the forces acting on this object balanced or unbalanced?

• Balanced

• Unbalanced

Multiple Choice

Are the forces acting on this object balanced or unbalanced?

• Balanced

• Unbalanced

Multiple Choice

The list describes six different situations.

1. A pendulum moving back and forth

2. A toy car rolling down a ramp

3. An airplane traveling at a constant velocity of 500 km/h north

4. A raindrop falling on a leaf

5. A marble sitting on a table

6. A hockey puck sliding across the ice at constant velocity

Which objects in the list are experiencing balanced forces?

• The pendulum, the toy car, and the hockey puck

• The airplane, the marble, and the hockey puck

• The toy car, the raindrop, and the marble

• The pendulum, the toy car, and the raindrop

Multiple Choice

Are the forces acting on the rope balanced or unbalanced?

• Balanced
• Unbalanced

Multiple Choice

These forces are...

• Balanced

• Unbalanced