Post on 14-Jul-2015
The Invisible Force of Gravity
By Emily Weil
9/10/09
Science Standard 3- The Physical Setting
• Indicator 5.3.6- Demonstrate that things on or near Earth are pulled towards it by Earth’s gravity.
• Taken from: http://www.indianastandards.org/standardSummary.asp?Subject=sci&Grade=5.
• Link to Activity: http://www.indianastandards.org/files/sci/sci_5_3_pull.pdf.
Definitions
• Gravity- Force of attraction that causes objects on Earth to fall towards the center (or downward).
• Force-Push or Pull on an Object.
• Balancing Point (Center of Gravity)- Point of an object that is closest to the ground (where weight equal on all sides).
• Weight-
• Mass- Amount of matter in an object.
Testing Gravity
• The mass of an object determines its gravity.
• Weight has a direct relationship with gravity (mass is not the same thing as weight)
– An object of the same mass can have different weights when there are different gravities
• Gravity can vary from place to place (the moon and other planets all have different gravities).
– Your weight (you keep the same mass) is different on Earth than it is on the moon.
Try it out!
• Look at the given chart and equations:– Pluto- weight/7.5– Mercury- weight/2.9– Mars- weight/2.63
• Calculate your weight using the equations.• What happens? Is your weight greater with greater
force of gravity?• Now let’s test whether gravity affects the speed of
descent. – Use to two objects (weight them) given and drop them
from the same height• Do they fall at different speeds?