Science 421: Physics

Physics examines heat, sound, light, energy, motion, forces, and energy with atoms. https://www.youtube.com/watch?v=yWM KYID5fr8

https://www.cbsnews.com/vide o/rube-goldberg-the-father-of- inventions/ (6:54)

Can be considered a push or a pull Have both a size and a direction Force (F): Can be considered a push or a pull Have both a size and a direction Contact and non-contact forces Measured in Newtons (N) Friction: A force caused by rubbing between two objects This force resists motion. https://www.youtube.com/watch?v=II6hP0Wxle8 (1:20) How does changing the force affect the motion of an object?

Contact Forces Collision Friction Tension Spring Forces between two objects that are touching.

Nuclear Gravitational Magnetic Electrostatic Non-contact Forces

Balanced vs Unbalanced Forces: Balanced force is when all the forces acting on an object equals zero. This does not produce a change in motion. Unbalanced force is when all the forces acting on an object does not equal zero. This does produce a change in motion.

Mass vs Weight Mass (m): A measure of an object’s inertia Measured in kilograms (kg) Weight (w): The force of gravity acting on a mass. Measured in Newtons (N) Inertia: the tendency for an object to keep moving or not start moving. Objects with little mass have small inertia; objects with a large mass have large inertia. How does changing the mass of an object change the affect of a force?

A change in speed or direction Gravity (g): A non-contact force that is the pull that two objects have on each other As an object falls to the ground, it picks up speed (acceleration). The force acting on this object is gravity. All objects in free-fall on Earth have the same gravitational acceleration which is 9.81 m/s2 in the absence of air resistance. Acceleration (a): A change in speed or direction Speeding up and slowing down are considered acceleration Measured in m/s2 The gravitational acceleration on Earth varies slightly due to the distance from the Earth’s center. The acceleration of gravity differs from planet to planet. For example, on the Moon 1.64 m/s2, Mars 3.72 m/s2, and Jupitar 25.9 m/s2.

An object in motion remains in motion and an object at rest remains at rest unless acted upon by an external force. (Inertia) https://www.youtube.com/watch?v=Q0Wz5P0JdeU (5:50) Newton’s First Law

The relationship between an object’s mass, its acceleration, and the force applied to an object. F = ma https://www.youtube.com/watch?v=WzvhuQ5RWJE (5:50) Newton’s Second Law Net Force: sum of all the forces acting on an object.

Force = mass x acceleration: A small force on a mass results in a small acceleration. A large force on the same mass results in a larger acceleration. If we are to rearrange the formula for acceleration: The larger the mass, the lesser the acceleration and the smaller the mass the greater the acceleration.

What is Energy? Energy is defined as the capacity to do work. Measured in Joules (J) https://www.youtube.com/watch?v=CW0_S5YpYVo (4:34) Objects at rest have energy.

Common Types of Energy Nuclear Solar Elastic Electromagnetic Mechanical Gravitational Kinetic Common Types of Energy

Energy of an object due to its motion Measured in Joules (J) Key Terms: Kinetic Energy: Energy of an object due to its motion Measured in Joules (J) Directly related to its mass and velocity Velocity: the speed and direction of a moving object. How can I increase the kinetic energy of an object? Discussion: Which has a greater impact in the kinetic energy of an object, mass or velocity? Why? Calculate the kinetic energy of the biker if the mass of the bicycle and rider is 93 kg and is travelling at a velocity of 2 m/s.

Gravitational Potential Energy: Key Terms: Gravitational Potential Energy: Energy stored by an object ready to be used Measured in Joules (J) Directly related to its mass and height https://www.youtube.com/watch?v=Ehx1P4adv6I (1:22) How can I increase the potential energy of an object? Potential energy has the potential to be converted to kinetic energy. Eg increases when there is an increase in height of the object. Calculate the potential energy in the picture above if the mass of the ball is 0.450 kg and is raised to a height of 1.5 m from the ground.

Conservation of Energy: In a closed system, one where energy cannot enter or leave, the amount of energy remains constant. The energy within this system cannot be created or destroyed but can change form. Diagram: Potential energy (at rest) at the top is converted to kinetic energy when it starts down the hill. Another example: When wood burns, the chemical energy transforms into thermal (heat) energy and radiant (light) energy.

The Engineering Design Process https://www.youtube.com/watch?v=MAhpfFt_mWM (3:32)

Rube Goldberg Born in July 4, 1883 Engineer for 6 months designing sewers Left engineering to become a cartoonist

What is a Rube Goldberg machine? ‘A symbol of man’s capacity for exerting maximum effort to achieve minimal results.’ What is a Rube Goldberg machine?

“Simplified” Pencil Sharpener Open window (A) and fly kite (B).  String (C) lifts small door (D) allowing moths (E) to escape and eat red flannel shirt (F).   As weight of shirt becomes less, shoe (G) steps on switch (H) which heats electric iron (I) and burns hole in pants (J).   Smoke (K) enters hole in tree (L), smoking out opossum (M) which jumps into basket (N), pulling rope (O) and lifting cage (P), allowing woodpecker (Q) to chew wood from pencil (R), exposing lead.  Emergency knife (S) is always handy in case opossum or the woodpecker gets sick and can't work.

175 step soda machine: https://www.youtube.com/watch?time_continue=32&v=98FPrilKJVs (3:23)