1. CST TEST PREP POWER POINT Science 8 th Grade

2. Motion  Speed = Distance/Time  Average speed = TOTAL distance traveled the time it took to travel  Slope = rise run  Velocity - describes how fast an object is moving AND the direction it is moving  Acceleration – how quickly an object’s VELOCITY changes

29. Forces Magnitude = strength of the force an object remains at rest or has constant motion unless an unbalanced force acts on the object. (Newton’s 1 st Law) when an unbalanced force acts on an object, the object will speed up, slow down, or change direction depending on the overall force acting on it. (Newton’s 2 nd Law) To find the total force and the direction of the force: Choose a positive direction and a negative direction and put appropriate signs in front of the forces Add all forces taking into account the plus and minus signs The magnitude tells you the strength, the sign tells you the direction of motion

54. Solar System Galaxy = cluster of billions of stars Galaxy Shapes = spiral, elliptical, and irregular Stars are different colors, sizes, and temperatures Stars are the ONLY object that can make it’s own light (they all use the same process called nuclear fusion) 1 AU = distance from Earth to Sun…used to measure distances within a solar system Light Year = distance light travels in a year…used to measure between galaxies and between stars

55. Solar System Asteroid Belt Terrestrial Planets Giant Gas Planets Kuiper Belt – in between Neptune and Pluto

77. Density and Buoyancy Formulas, difference between mass/ volume What is bouyancy? Keep reading… What is density? It’s how compact a material is based on it’s measured mass and volume. 1.Mass= how much of a material there is. Put it on a scale to find out (measured in grams (g), kilograms (kg), etc… 2.Volume= how much space that material takes up. Drop the material in some water, or get a ruler (measured in milliliters (ml), liters (l), or cm 3 )

78. So if I know my mass and volume, then I can get my density. Why??? Density=Mass/Volume Example= a basketball has the mass of 30 grams and the volume of 40cm 3. What’s its density=

79. Density of the basketball=30grams/ 40cm 3 =.75grams/cm 3 Always have the units of measurement after the density number. WRONG=.75 RIGHT=.75g/cm 3 Oh, hey, would this basketball having a density of.75g/cm 3 float on water? Explain.

80. YESS! Freshwater’s Density is always 1g/ml. Anything that has a density less than 1g/ml will float (So.75g/cm 3 will float cuz it’s less). BUT anything with a density greater than 1g/ml will sink (like a cell-phone with a density of 1.3g/cm 3 )

81. So what is Buoyancy? -It’s the upward force exerted by a fluid on an object trying to go down. When the net force of the fluid going up EQUALS the magnitude of the weight of fluid displaced By an object (like that ball right there).

82. Buoyancy is how you get boats to float. The magnitude of the weight of the boat has TO DISPLACE the right amount of water to equal the force exerted by the water going up. To figure if it will float or not, you need to know about each materials density. Hmmmmmm….. BUOYANTFAIL