Describing Motion.pdf

Describing Motion Objective In this lesson, you will Introduction The study of motion is called ___________________, and it's central to understanding physics. In physics, motion is defined as a change in the _______________ of a body with respect to a reference point. Properties of Motion A simp...

Describing Motion Objective In this lesson, you will Introduction The study of motion is called ___________________, and it's central to understanding physics. In physics, motion is defined as a change in the _______________ of a body with respect to a reference point. Properties of Motion A simple definition of motion is any movement or change in an object's ______________. The Italian scientist ______________ Galilei recorded careful observations and experimented with motion. His observations caused him to challenge what ________________ had proven 2,000 years earlier. Distance and Displacement In physics, _________________ is the length measured between two points. Distance is a _____________ quantity, a quantity that specifies only a magnitude but does not specify direction. Magnitude is a numerical value. Displacement is defined as the _________________ path from an initial position to a later position. Displacement is a _____________ quantity, a quantity that specifies both magnitude and direction. Speed 𝑑 Speed is an object's rate of change in distance over ________. The formula for speed is 𝑠 =. 𝑡 Note that speed, like distance, is a _____________ quantity. It specifies magnitude but not _______________. Velocity Velocity is different from speed because it specifies _____________ in addition to ____________. During the morning, a bus moves to the east at 20 meters/second from its starting point. In the evening, from the same starting point, the bus moves 20 meters/second to the west. This example tells us that velocity is the ____________ of an object and the direction in which the object changes its position. → To calculate velocity, we consider displacement and distance. Because displacement is the change in the position of an object, __________________ is defined as the displacement of an object over time. → Bus example: if east is the __________ direction, the velocity in the morning is +20 meters/second, and the velocity in the evening is –20 meters/second. Acceleration When an object's ________________ changes, its speed, direction, OR both speed and direction change. → Change in velocity over a ___________ of __________ is acceleration. Like velocity, acceleration is a ___________ quantity. → To calculate acceleration, divide the change in velocity by the change in time. change in velocity average acceleration = change in time Example: a car starts at rest (initial velocity = 0 meters/second) and accelerates at a nearly constant rate for 3.0 seconds. At 3 seconds it has a velocity of +7.2 meters/second (to the east). 7.2 𝑚/𝑠 The car's average acceleration = = __________s2 3𝑠 Aristotle's theories reflected everyday experience and common sense logic. They were believed, studied, and taught—until Galileo's ______________ experiments proved differently. Galileo described dropping objects of different weights from the top of the Leaning Tower of Pisa in Italy. His observations led him to realize that objects of different weights _______________ simultaneously landed on the ground with just a slight difference in __________. Due to air resistance, not the weight of the object, a rock will fall faster than a feather. In a ______________, the feather and the rock would hit the ground at the same time. Types of Motion Translation: Translation is motion from one ___________ to another. There are two types of translation. → linear motion: where the object moves in a ______________ line → curvilinear motion: where the object moves along any ________ that is ______ linear Rotation: When an object ____________ around an axis without altering its position in space, it is rotating. Vibration: Stringed instruments, such as the guitar, violin, and cello, display vibrational motion (vibrates bank and for quickly) to create music. Sometimes an object may display more than one kind of ___________. Inertia In everyday use, the word inertia means the tendency to stay __________ or to not get anything done. Galileo concluded that an object _____________ any change to its state of motion. If an object is standing still, it will oppose being ____________. If it's moving, however, it will oppose any change to its ____________________. Specifically, an object in motion will continue to travel in a straight line at a ______________ velocity unless it's acted upon by some outside ___________. This is Galileo's law of ____________, and it became the basis for Isaac Newton's ___________ law of motion. → It allowed Newton to understand the relationship between __________ and ____________ and to extend the laws of physics from Earth and the Sun to planets and stars. Forces (and especially what we know as friction) cause objects to ________ down and stop. Without external forces such as ________________ acting on them, objects would continue to move at a constant ________________—a constant speed in a straight line. Summary What discoveries by Galileo have been foundational in the field of physics?