Fall 2025 Review in Tweets
Happy first day of school! This semester, I'm teaching:
— Tom Wong (@thomasgwong) August 19, 2025
1. #PHY131 Quantum Physics and Technology for Everyone #QuantumForEveryone, a new 2-credit general education course
2. #PHY201 General Physics for the Life Sciences 1 #GenPhys1
3. #PHY531 #QuantumMechanics
Today in #PHY201 #GenPhys1: SI units are the same across the universe. Prefixes multiply units by powers of 10. Dimensional analysis helps rule out incorrect equations. Distance--a scalar--is the length of path traveled. Displacement--a vector--is change in position.
— Tom Wong (@thomasgwong) August 25, 2025
Today in #PHY201 #GenPhys1: Velocity is change in position (Δx) over change in time (Δt). On a position vs time graph, Δx is the rise, and Δt is the run, so velocity is the slope. With constant velocity, v = v₀ and x = v₀ t + x₀.
— Tom Wong (@thomasgwong) August 27, 2025
Today in #PHY201 #GenPhys1: Assuming constant acceleration, we derived four kinematic equations involving different variables. They also apply to free fall motion, where acceleration due to gravity near the surface of the earth is approximately constant. pic.twitter.com/uBFrKaQFDf
— Tom Wong (@thomasgwong) September 3, 2025
Today in #PHY201: For the motion of a projectile, there is constant velocity in the x-direction and constant acceleration (due to gravity) in the y-direction, resulting in six kinematic equations describing the motion. pic.twitter.com/yOmI9C4AzI
— Tom Wong (@thomasgwong) September 11, 2025
Yesterday in #PHY201 #GenPhys1: When driving in a circle at constant speed, there is still an acceleration since velocity is a vector and its direction is changing. It's centripetal acceleration v^2/r. If you also speed up or slow down, there's a tangential acceleration as well.
— Tom Wong (@thomasgwong) September 16, 2025
Yesterday in #PHY201 #GenPhys1: Newton's three laws. (1) If the net force on an object is zero, it's acceleration is zero. (2) Net force equals mass times acceleration. (3) If you push or pull on an object, it pushes or pulls back with the same force, but opposite direction.
— Tom Wong (@thomasgwong) September 19, 2025
Today in #PHY201 #GenPhys1: When an object lies on a surface, the surface exerts a force perpendicular to its surface, which is called the normal force. We explored normal force at rest, in an accelerating elevator, with other forces present, and on inclines.
— Tom Wong (@thomasgwong) September 24, 2025
Today in #PHY201 #GenPhys1: Applications of Newton's law involving the normal force on level and incline surfaces, objects pushing and pulling each other, and tension, including static equilibrium.
— Tom Wong (@thomasgwong) September 29, 2025
Today in #PHY201 #GenPhys1: Review of Newton's Laws and their applications, including normal force, tension, friction, and circular motion. pic.twitter.com/bGnCBAIEPA
— Tom Wong (@thomasgwong) October 7, 2025
Yesterday in #PHY201 #GenPhys1: The work that a force does on a moving object equals the amount of the force along the motion, times the displacement. Forces that push with the movement do positive work, against do negative work, and perpendicular to do zero work.
— Tom Wong (@thomasgwong) October 10, 2025
Today in #PHY201 #GenPhys1: The net work on an object changes its kinetic energy. This directly relates force (via work) and velocity (via kinetic energy). Before, we needed Newton's laws to go from force to acceleration, and then kinematics to go from acceleration to velocity.
— Tom Wong (@thomasgwong) October 21, 2025
Students in General Physics for the Life Sciences #PHY201 #GenPhys1 can be a tough crowd, but today, a student told me, "I no longer hate physics." While that doesn't mean they love physics, I'll take the win!
— Tom Wong (@thomasgwong) October 21, 2025
Yesterday in #PHY201 #GenPhys1: The work done by a conservative force is path independent. It defines a scalar at all points from a reference point. The negative is potential energy. (Initial mechanical energy) + (work done by non-conservative forces) = (final mechanical energy).
— Tom Wong (@thomasgwong) October 23, 2025
Yesterday in #PHY201 #GenPhys1: A net force applied for some time changes the momentum of the system. In an isolated system, momentum is conserved. We calculated how fast Fulton Reed's hockey puck must travel in The Mighty Ducks to knock a goalie into the goal. pic.twitter.com/0JoFVzH46f
— Tom Wong (@thomasgwong) October 28, 2025
Today in #PHY201 #GenPhys1: In a 1D elastic collision of two objects, relative velocity flips. In a ballistic pendulum, cons' of momentum is followed by cons' of energy. In a 2D collision, use components. Spreading an impulse over a longer time decreases the average force.
— Tom Wong (@thomasgwong) October 30, 2025
Page Last Updated: October 29, 2025