Understanding Forces and Motion

• Force, motion, and energy are fundamental concepts in physical sciences to understand how objects behave.

Force

• A push or pull that can make objects move, stop, or change direction.
• Gravity pulls objects towards each other, keeping things on the ground.
• Friction slows down or stops motion when two surfaces rub together.
• Applied force exerted by a person or object on another object.
• Balanced forces of equal size but opposite direction result in no change in motion.
• Unbalanced forces that are unequal cause acceleration in the direction of the larger force.
• Net force is the combined overall force acting on an object.
• Weight is the force exerted on an object by gravity, pulling it towards the Earth's center.
• Newton is the unit used to measure force.
• Pushing an object moves it away from the force
• When jumping, pushing down propels body upwards
• Kicking a ball moves it forward
• Pulling an object moves it towards the force.
• Jumping will cause gravity to pull you back down
• Pulling a wagon makes it move toward you
• Forces can speed up, slow down, maintain, an object's shape or change it.
• The application of force is needed to change an object's motion.
• Newtons are what all forces are measured in

Friction

• Friction opposes an object's motion, slowing down or stopping it.
• It occurs when two objects' surfaces touch, rub, or slide against each other.
• Smooth surfaces results in less friction and allow objects to slip or slide faster.
• Rough surfaces results in more friction and slows objects down.

Sliding Friction

• Opposes the motion of sliding objects, causing them to slow down and stop.
• Rough surfaces create sliding friction.

Rolling Friction

• Opposes the motion of objects rolling over a surface.
• Rolling friction is usually less than sliding friction.

Fluid Friction

• Opposes the motion of objects moving through a fluid like air or water.
• The resistance felt when swimming or biking against the wind is due to fluid friction.

Air Resistance

• Air resistance caused by air particles hinders an object's motion as it moves through the air.
• Gravity pulls skydivers and parachutes down, but air resistance slows them.
• Parachutes increase air resistance to slow the descent.

Contact vs. Non-contact Force

• Contact force: physically applying force to an object, such as pushing a swing.
• Non-contact force: affects an object without physical contact.
• Gravity pulls objects down without touching them.
• Magnets attract metal objects without touching them.

Balanced vs. Unbalanced Force

• Balanced force: Equal in size and opposite in direction, causing no movement.
• Unbalanced force: unequal in size, causing movement in the direction of the stronger force.

Gravity

• Invisible, non-contact force drawing things towards the center of an object, like the earth.
• Always attracts two objects towards each other.
• Anything with mass has a gravitational pull; more mass equals more gravity.
• Sir Isaac Newton formulated the Law of Universal Gravitation, describing the attraction between objects with mass.

Energy

• Energy is the ability to do work or make changes, classified as kinetic (motion) or potential (stored).

Forms of Energy

• Mechanical energy has the sum of energy in motion and stored motion by an object.
• Chemical energy: stored in bonds of chemical compounds, like atoms and molecules.
• Electrical energy: possessed by moving electrons carried by electrical currents.
• Heat/Thermal energy: makes things warm or hot, due to movement of molecules.
• Sound energy: produced by vibrating objects.
• Light/Radiant energy: electromagnetic radiation produced by hot objects.

Energy Transformation

• Law of Conservation of Energy: energy cannot be created or destroyed, only transformed.

Renewable vs. Nonrenewable Energy

• Renewable energy: comes from sources that are constantly replenished and won't run out, as well as can be used over and over again without pollution
• Solar, hydroelectric, and wind are examples of renewable resources
• Nonrenewable energy: from sources that will run out because they take millions of years to form, and may contribute to climate change
• Coal, oil, natural gas, and nuclear energy are examples of nonrenewable resources

Work and Power

• Work: when force moves an object, using joules (J) as the measurement unit, and equalling force times distance.
• Power: how quickly or how much work is done, measured in watts (W), and equaling work times time.

Motion Key Terms

• Motion: when an object changes its position over time.
• Speed: how fast an object is moving, usually in meters per second (m/s) or miles per hour (mph).
• Velocity: object's speed in a specific direction.
• Acceleration: how quickly speed or velocity changes over time.
• Distance: how far an object moves, in meters (m) or kilometers (km).
• Displacement: change in position of an object in a straight line.

Introduction To Motion

• Motion of an object with mass can be described in the terms of: distance, displacement, speed, velocity, time, and acceleration.
• Motion is determined by how the position varies between two objects or observers.
• Point of reference and defined directions are needed when dealing with motion on an axis

Distance and Displacement

• Determining how far the object moves is distance.
• Determining how far the object is from the starting point is displacement.
• The total amount of ground covered is distance.
• Displacement show how far you are from where you started and the direction you moved.

Magnitude and Directions

• Magnitude refers to the size or distance from the starting point
• Direction is where you are relative of the starting point

Speed, Velocity and Acceleration

• Speed expresses how fast an object is moving.
• The average speed consists of the total distance divided by the total time
• The instantaneous speed is the speed of an object at a specific moment.
• Velocity is speed that also include direction.
• Acceleration is how quickly speed or velocity changes over time.

Newtons Laws Of Motion

• Law of Inertia explains how an object that is still will stay still, or an object in motion will stay in motion, unless a force acts upon it
• Law of Acceleration expresses how acceleration will increase with more force being applied to the object.
• Law of Action-Reaction elucidates how every action has an equal and opposite reaction

Measuring Devices

• Spring Scale measures force
• Speedometer measures speed
• Thermometer measures temperature
• Stopwatch measures time
• Anemometer measures when speed and direction
• Accelerometer measures acceleration
• Ruler measures distances

Explore the fundamental concepts of balanced and unbalanced forces, gravity, friction, and applied forces. Test your knowledge of scenarios involving motion, air resistance, and non-contact forces. Learn how forces influence the movement of objects.