Post on 12-Jan-2016
DENSITY AND SPECIFIC GRAVITY
• A property of matter representing the mass per unit volume
• g/ml –liquid -grams/milliliters
• g/cm3 -solid -grams/centimeters cubed
• 1ml = 1cm3
• Must be in grams, centimeters, and milliliters *no other units allowed
To Find the Mass (numerator)
• Grams -mass
-solid -place item on balance scales
-liquid 1. find the mass of an empty cylinder
2. find the mass of the cylinder with the liquid in it
3. subtract the two readings = the mass of the liquid
To Find Volume (denominator)
• Volume -ml or cm3
• Use a cylinder for liquid and read the meniscus (lowest level of liquid in the cylinder)
Volume of an Irregular Solid
• Use water displacement for a solid 1. put water in a cylinder and read
2. drop a solid in the water and read again
3. subtract the two readings
continued
• Water weighs 1 gram per milliliter
• Water’s mass is 1 gram per milliliter
• Water’s density is 1 gram per milliliter
• Anything more dense than 1 gram per milliliter will sink in water
• Anything less dense than 1gram per milliliter will float on water
Volume of a Regular Solid
• Volume for a regular solid
using a meter stick, measure the height, width, and length
H x W x L = the volume
1 side x 1 side x 1 side = the volume of a cube
if all the sides are the same = the side cubed (g/cm3)
Review
• Volume of a rectangleL x W x H
Volume of a cylinder (radius = diameter/2)pi x R2 x H
Volume of a sphere 4/3 x pi x R2 (radius = circumference/pi/2)
Check in passbook for equations
Label for Density
• So, Density = g/cm3 or g/ml
Problems to Solve
• Density = ?cm3 = 5g = 15
(per means to divide) g/cm3
Grams = ?density = 6 g/mlml = 2
• Volume = 50cm3
Mass = 100grams
What is the density of this object
Volume = 32 liters
Mass = 40 centigrams (must change centigrams to grams before
completing the problem)
• Volume reading in cylinder
water only 4ml
water with rock8ml
mass = 12 g
Will it float or sink in water?
What is the density?