Warm Up.095 Km = ____ dm.095 Km = ____ dm 0.50 mg = _____ g 0.50 mg = _____ g 23 L = ______mL 23 L = ______mL 62.5 decameter= _____cm 62.5 decameter= _____cm 325m = _______Km 325m = _______Km 297 g = ________Kg 297 g = ________Kg

Mass, Weight and Density

 Developed by the French in the late 1700’s.  Based on powers of ten, so it is very easy to use.  Used by almost every country in the world, with the notable exception of the USA.  Especially used by scientists.  Abbreviated SI, which is French for Systeme International. Metric System

  Mass is a measure of the amount of substance in a body.   SI Unit: Kilogram (kg)   Large masses are measured in tons while small masses are measured in grams. MASS

We will use a double beam balance Measuring Mass

Gravitational force acting on an object W = mg where m is the mass of the object g is the gravitational field strength. g is the gravitational field strength. Weight is measured in newtons (N) Weight is...

 The gravitational field is a region in which a mass experiences a force due to gravitational attraction.  Gravitational field strength is gravitational force acting per unit mass on an object.  On earth, the gravitational field strength is 9.5 m/s m/s2. Gravitational Field Strength

 Volume is the amount of space an object consumes.  The base unit for volume is the liter.  There are two methods for finding volume. Volume

 We can find the volume of box shapes with the formula Volume = length x width x height.  In this case the units would be cubic centimeters (cm3). So a box 2 cm x 3 cm x 5cm would have a volume of 30 cm3 So a box 2 cm x 3 cm x 5cm would have a volume of 30 cm3 2 cm 5 cm 3 cm Volume of Regular Objects

 We measure volume of irregular objects with a graduated cylinder.  This method is called water displacement  Liquids form a curved surface in graduated cylinders.  Take your reading at the low point of the curve or MENISCUS

Water Displacement Pour 7 ml of water in a graduated cylinder. If a rock causes the level to rise to 9 ml, the rock must have a volume of 2 ml.

 Weight is measured using a balance such as the  spring balance  compression balance Measurement Instruments

Differences between Weight and Mass WeightMass  pull of gravity on the body  amount of matter in the body

DENSITY Q) Which weighs more:- A kilogram of feathers or a kilogram of iron?

What is Density? Density is the Mass per unit Volume WoodWaterIron 1 cm 3 1 cm 3 1 cm 3 If you take the same volume of different substances, then they will weigh different amounts g1.00 g8.00 g Q) Which has the greatest mass and therefore the most dense? IRON

Density = Mass Volume g or kg cm 3 gcm -3 or kgm -3 Density Equation:

DENSITY OF A REGULAR SOLID Find the Mass of the solid on a balance. Find the Mass of the solid on a balance. Measure the three lengths and calculate the Volume. Measure the three lengths and calculate the Volume. (ie V = l x w x h ) Calculate the Density. Calculate the Density. 4.0 cm 2.0 cm 3.0 cm  = m = 240 =10.0 g/cm 3 V 24 m = 240 g

Density Formula Wheel Formula wheels make it easy to solve density problems. Cover the property you are trying to find, and do what is left over. To find density, cover the word density. You have mass over volume remaining. So divide mass by volume to find density DensityVolume

DENSITY OF AN IRREGULAR SOLID Find the Mass of the solid on a balance. Find the Mass of the solid on a balance. Fill the Measuring Cylinder with Water to a known Volume. Fill the Measuring Cylinder with Water to a known Volume. Add the Object. Add the Object. Work out the Volume of Water that is displaced. Work out the Volume of Water that is displaced. Calculate the Density. Calculate the Density. 50 cm 3 80 cm 3 m = 360 g  = m = 360 =12.0 g/cm 3 V 30

Now You Try You have a rock with a volume of 15cm 3 and a mass of 45 g. What is its density? You have a rock with a volume of 15cm 3 and a mass of 45 g. What is its density? You have a different rock with a volume of 30cm 3 and a mass of 60g. What is its density? You have a different rock with a volume of 30cm 3 and a mass of 60g. What is its density? In the above two examples which rock has the greater density? In the above two examples which rock has the greater density?

Now You Try You decide you want to carry a boulder home from the beach. It is 30 centimeters on each side, and so has a volume of 27,000 cm 3. It is made of granite, which has a typical density of 2.8 g/cm 3. How much will this boulder weigh? You decide you want to carry a boulder home from the beach. It is 30 centimeters on each side, and so has a volume of 27,000 cm 3. It is made of granite, which has a typical density of 2.8 g/cm 3. How much will this boulder weigh?

Now You Try A golden-colored cube is handed to you. The person wants you to buy it for $100, saying that is a gold nugget. You pull out your old geology text and look up gold in the mineral table, and read that its density is 19.3 g/cm 3. You measure the cube and find that it is 2 cm on each side, and weighs 40 g. What is its density? Is it gold? Should you buy it? A golden-colored cube is handed to you. The person wants you to buy it for $100, saying that is a gold nugget. You pull out your old geology text and look up gold in the mineral table, and read that its density is 19.3 g/cm 3. You measure the cube and find that it is 2 cm on each side, and weighs 40 g. What is its density? Is it gold? Should you buy it?

DENSITY OF AN IRREGULAR SOLID OR use a Eureka Can to find the Volume. OR use a Eureka Can to find the Volume. Find the mass of the solid on a balance. Find the mass of the solid on a balance. Add water until just overflowing. Add water until just overflowing. Place a Measuring Cylinder under the spout. Place a Measuring Cylinder under the spout. Add the Object. Add the Object. Collect the Water and read off the Volume. Collect the Water and read off the Volume. Calculate Density Calculate Density m = 440 g 40.0 cm 3  = m = 440 =11.0 g/cm3 V 40

DENSITY OF A LIQUID Find the Mass of an empty Measuring Cylinder. Find the Mass of an empty Measuring Cylinder. Add a certain Volume of Liquid. Add a certain Volume of Liquid. Find the Mass of the Measuring Cylinder and Liquid Find the Mass of the Measuring Cylinder and Liquid Calculate the Mass of Liquid. Calculate the Mass of Liquid. How? How? Calculate Density of Liquid. Calculate Density of Liquid g 20.0 cm g 45 – 25 = 20 g  = m = 20 =1.00 g/cm3 V 20 Mass of Liquid = Mass of Measuring Cylinder and Liquid – Mass of empty Measuring Cylinder