AIM: Describe the factors that effect the strength of gravity and how inertia differs from gravity?

OBJ: Given notes, images and activity sheet SWBAT describe the factors that effect the strength of gravity and how inertia differs from gravity with 70% accuracy

DN: HW check- Earth in Space Activity Sheet

ACT: Introduction to Gravity and Inertia (notes)Complete Earth’s Motions Activity Sheet

HW: Text, read 16-19, Complete Gravity & Motion Activity Sheet; Work on Astronomy Activity Sheet; Astronomy Exam, Dec 19. Weather & Climate (Red) Textbooks due Dec 18,19.

GRAVITYForce: a push or pull

Gravity: attractive force between objects containing mass [In reality, gravity is the warping of spacetime by objects in the universe].

Gravitational Force Unit: newton, N

Two factors affect gravity: 1) mass of the object’s, 2) distance between objects.

F(g) = M1 x M2_

d2

Gravity

Gravity

MassMass: amount of matter (atoms) in an object

Weight: force of gravity on an object’s mass. Weight = mass x gravity

Note: object’s mass doesn’t change but

object’s weight changes due to change in gravity because planets/moon vary in size.

DistanceGravity decreases, as distance increases

Gravity increases, as distance decreases

Inverse relationship

distance

gra

vity

InertiaInertia: tendency of an object to resist a change in motion.

Newton’s first law of motion: Objects at rest, remain at rest

Objects in motion, remain in motion (at constant speed & direction) . . . unless acted on by a force.

Inertia

Orbital MotionOrbit is due to two (2) factors:

1] gravity

2] inertia

inertia