Net Force and Balanced vs. Unbalanced Forces

• Net force is the overall force acting on an object.
• When forces are balanced, they cancel each other out.
• A net force of zero means the object is at rest or moving at a constant speed in a straight line.
• An object at rest does not necessarily mean the net force is zero, and an object with balanced forces is not necessarily at rest.
• Net force is the sum of all forces acting on an object.

Balanced vs. Unbalanced Forces

• Balanced forces result in no change in motion; an object remains at rest or continues moving at a constant velocity.
• Think of a car cruising on a straight highway at a steady speed; the engine's forward force and friction are balanced, so the car keeps moving at a constant speed.
• Unbalanced forces cause acceleration; an object speeds up, slows down, or changes direction due to an unbalanced force.
• Net force of zero means no change in motion.
• Unbalanced forces cause a change in motion, including acceleration.
• Balanced Force - constant (stationary) no changing or not moving; NO NET FORCE
• Unbalanced Force - there was a change, either speed up or slow down:WITH NET FORCE

Identifying Balanced and Unbalanced Forces:

• A book resting on a table: Balanced
• A car accelerating from a stoplight: Unbalanced
• A person pushing a stationary shopping cart: Unbalanced
• A ball rolling on a flat surface at a constant speed: Balanced
• A child swinging on a swing at a constant height: Balanced
• A box being pulled to the right while friction pulls to the left: Unbalanced
• A plane flying at a constant altitude and speed: Balanced
• A soccer ball being kicked: Unbalanced
• A ladder leaning against a wall without slipping: Balanced
• A person standing still on a scale: Balanced

True or False Questions:

• If the net force on an object is zero, the object is at rest; False
• Balanced forces always cause a change in motion; False
• Unbalanced forces always result in acceleration; True
• An object with balanced forces acting on it can be moving at a constant velocity; True
• Net force is the sum of all forces acting on an object; True
• If an object is not moving, there are no forces acting on it; False
• A book resting on a shelf experiences balanced forces; True
• A car accelerating from a stoplight experiences unbalanced forces; True
• Friction is always a balanced force; False
• Gravity is always an unbalanced force; False
• A skydiver falling at terminal velocity experiences balanced forces; True
• The net force on a freely falling object is equal to its weight; True
• If two forces of equal magnitude act on an object in opposite directions, the net force is zero; True
• An object can have a net force of zero and still be moving; True
• Unbalanced forces can cause an object to change direction; True

Weight vs. Mass:

• Mass is the amount of matter in an object, measured in kilograms (kg).
• Weight is the force exerted on an object due to gravity.

Heat vs. Thermal Energy:

• Thermal energy is the total energy of all the particles in an object, dependent on the number of particles, their temperature, and arrangement.
• Heat is the transfer of thermal energy from a hotter object to a colder object.

Kinetic vs. Potential Energy:

• Kinetic energy is the energy of motion.
• Potential energy is stored energy due to an object's position or state.

Acceleration:

• Acceleration is the change of speed, measured in m/s².

Laws of Motion

• These laws describe the behavior of moving objects and how they interact with forces.

Newton's Laws of Motion:

• 1st Law (Inertia): An object remains at rest or in motion at a constant velocity unless acted upon by a net force.
• 2nd Law: An object with unbalanced force is meaning changing acceleration
• 3rd Law: For every action, there is an equal and opposite reaction.

Force

• Force is a pull or push, measured in Newtons.
• Energy : is the ability to do work.

Forms of Energy:

• Kinetic energy is the energy of motion.
• Potential energy is stored energy.
• Thermal energy
• Electrical energy
• Chemical energy Elastic Potential Energy - spring - compressed or stretched
• rubber band - when stretched and when released energy is converted to kineteic.
• Heat is a form of energy that is transferred between objects due to a temperature difference, measured in Joules.

Electricity:

• Electricity is the flow of electric charge.

Thermal Energy:

• Thermal energy is the total kinetic and potential energy of the particles in a substance; it depends on factors like the number of particles, their motion, and their arrangement.

Simple Machines:

• Simple machines are basic mechanical devices that use a single applied force to do work against a single load force.
• Types of simple machines include:
• Lever
• Wheel and Axle
• Pulley
• Inclined Plane
• Wedge
• Screw