Mechanics: study of motion of objects, and the related concepts of forec and engergy 1. Kinematics: description of how objects move 2. Dynamics: deals with force and why objects move as they do
- translational motion is when objects move without rotation (a point particle can only undergo translational motion)
2.1: Reference Frames and Displacement #
measurements are taken from a certain viewpoint → called a reference frame in physics
- a man walking at 5 km/h on a bus going 80 km/h would be going 85 km/h, with respect to the ground
- one should always specify reference frame
we can change what direction positive and negative are, this is the conventional coordinate axes (with the origin at 0)
Recall : displacement is a vector, a quantity with both magnitude (length of a vector) and direction
2.2: Average Velocity #
- speed is not a vector, it lacks direction
- velocity is a vector
- Average Speed = distance traveled / time elapsed # convert to math form later
- Average Velocity = displacement / time elapsed
2.3: Instantaneous Velocity #
- Instantaneous Velocity = ____
- has the same magnitude as instantenous speed
- on a position vs time graph, instantenous velocity is equal to the slope
2.4: Acceleration #
- Acceleration is the change of velocity per unit of time
- Average Accelerationn = change in velocity / change in time
2.5: Motion at Constant Acceleration #
- Instantaneous acceleration is the average of acceleration taken over an infitesimally short time interval # math shi
2.6: Solving Problems #
- kinematics eqs !¡
2.7: Freely Falling Objects #
- in the absence of air reistance, all objects fall with the same constant acceleration