Balanced & Unbalanced Forces
These forces are equal and opposite, causing no change in motion.
What are balanced forces?
This law states that every action force has an equal and opposite reaction force.
What is Newton’s Third Law?
This force resists motion between two touching surfaces.
What is friction?
True or False: gravity is both attractive and repulsive
A push or pull that can change motion.
What is a force?
This happens when forces are not equal and motion changes.
What are unbalanced forces?
This law explains how force and mass affect motion.
What is Newton’s Second Law?
This type of force acts without objects touching.
What is a non-contact force?
Gravity becomes weaker when this increases.
What is distance?
The invisible area around a magnet where magnetic force acts. This force also exists in all matter.
What is a magnetic field?
The total combined force acting on an object.
What is net force?
This law explains why objects stay at rest or keep moving unless acted on by an unbalanced force.
What is Newton’s First Law?
This force pulls objects with mass toward one another.
What is gravity?
This keeps smaller objects with mass revolving around larger objects with mass due to the velocity of the smaller object and the distance between the two objects.
What is an orbit?
The invisible "grid" around an object where gravity affects other objects.
What is a gravitational field?
A tug-of-war has Team A pulling with 25 N and Team B pulling with 10 N.
Explain:
• whether the forces are balanced or unbalanced
• the net force
• Unbalanced
• Net Force of 15 with arrows pointing toward Team A
Two friends on roller skates push away from each other.
Explain:
• the action force
• the reaction force
• They both provide the action force
• They both provide the reaction force
Compare and contrast the "fields" of the two non-contact forces you've learned: magnetism and gravity
How are these two fields different? (Please refer to lesson 6.3 and 6.3)
Magnetic fields exist throughout the universe and all matter produces them.
The gravitational field is like a grid throughout the universe and is influenced by mass and distance between two objects.
Earth is approximately 150 million kilometers from the Sun.
Explain:
• why Earth does not fly away into space
• why Earth does not crash into the Sun
• Due to the velocity of the Earth and the distance between the Earth and Sun
A student says:
“Magnetic force and gravitational force are exactly the same.”
Explain:
• one similarity
• one difference
• Similarity: both forces are exist throughout the universe
• Difference: gravity is attractive while magnetism is both attractive and repulsive
A student claims: “If an object is moving, the forces acting on it must always be unbalanced.”
Using evidence from class investigations (Lesson 6.0), explain whether this statement is correct or incorrect.
This statement is incorrect due to the definition of balanced force as a forces that are equal and opposite, causing an object to stay still OR keep moving at the same speed.
A balloon rocket moves across a string after air is released.
Use Newton’s Laws to explain:
• why the balloon moves forward
• why the air moves backward
• whether the motion involves balanced or unbalanced forces
• The balloon pushes the air out
• The surrounding air then pushes back on the balloon
• The motion involves and unbalanced force
A car slides on ice after the brakes are applied.
Explain:
• which main contact force(s) is influencing this scenario and how
• Friction slowing the car due to the breaks on the wheels of the car.
• A lack of friction due to the lack of traction/grip from the wheels and the icy road.
A moon moves farther away from its planet.
Analyze how this change affects:
• gravitational force strength
A book slides across a table and eventually stops.
Identify and explain:
• at least two major forces acting on the book
• whether or not the net forces are balanced or unbalanced
Applied force (push) and friction are acting on the book. The net force is unbalanced as the applied force is greater than the friction force.