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- 1. Lecture #1 – June 11, 2014 DENSITY - is a scalar quantity and defined as the ratio of mass per unit volume. - it is also known as mass density. - in equation, ρ = 𝑚 𝑣 (𝑒𝑞. 1) where 𝜌 is the density 𝑚 is the mass 𝑣 is the volume
- 2. - the SI unit if density is 𝑘𝑔 𝑚3 . - 1 𝑔 𝑐𝑚3 = 10 𝑘𝑔 𝑚3 - as “weight density”, it is expressed as 𝜌 = 𝑊 𝑣 = 𝑚𝑔 𝑣 (𝑒𝑞. 2)
- 3. SPECIFIC GRAVITY - also known as “relative density”. - is the ratio of the density of the substance to that of water 1000 𝑘𝑔 𝑚3 - can be expressed by the equation 𝑆 𝑔 = 𝜌𝑠𝑢𝑏𝑠𝑡𝑎𝑛𝑐𝑒 𝜌 𝑤𝑎𝑡𝑒𝑟 (𝑒𝑞. 3)
- 4. DENSITIES OF SOME COMMON SUBSTANCESAT STANDARD TEMPERATURE 𝟎° 𝑪 SUBSTANCE 𝝆 𝒌𝒈 𝒎 𝟑 Air 𝟏. 𝟐𝟗 Aluminum 𝟐. 𝟕𝟎 × 𝟏𝟎 𝟑 Benzene 𝟎. 𝟖𝟕𝟗 × 𝟏𝟎 𝟑 Copper 𝟖. 𝟗𝟐 × 𝟏𝟎 𝟑 Ethyl alcohol 𝟎. 𝟖𝟎𝟔 × 𝟏𝟎 𝟑 Fresh water 𝟏. 𝟎𝟎 × 𝟏𝟎 𝟑 Glycerin 𝟏. 𝟐𝟔 × 𝟏𝟎 𝟑 Gold 𝟏𝟗. 𝟑 × 𝟏𝟎 𝟑 Helium gas 𝟏. 𝟕𝟗 × 𝟏𝟎−𝟏 Hydrogen gas 𝟖. 𝟗𝟗 × 𝟏𝟎−𝟐
- 5. SUBSTANCE 𝝆 𝒌𝒈 𝒎 𝟑 Ice 𝟎. 𝟗𝟏𝟕 × 𝟏𝟎 𝟑 Iron 𝟕. 𝟖𝟔 × 𝟏𝟎 𝟑 Lead 𝟏𝟏. 𝟑 × 𝟏𝟎 𝟑 Mercury 𝟏𝟑. 𝟔 × 𝟏𝟎 𝟑 Oak 𝟎. 𝟕𝟏𝟎 × 𝟏𝟎 𝟑 Oxygen gas 𝟏. 𝟒𝟑 Pine 𝟎. 𝟑𝟕𝟑 × 𝟏𝟎 𝟑 Platinum 𝟐𝟏. 𝟒 × 𝟏𝟎 𝟑 Seawater 𝟏. 𝟎𝟑 × 𝟏𝟎 𝟑 Silver 𝟏𝟎. 𝟓 × 𝟏𝟎 𝟑
- 6. Sample Problem 1. What is the mass of solid iron wrecking ball of radius 18cm? 2. A lead cube has a total mass of 50kg. What is the length of a side of a cube and the volume of a cube? 3. A rectangular block measures 2.3cm x 5.1cm x 7.8cm. It has a mass of 66g. 4. Calculate the density and specific gravity of a liquid if 38.94𝑐𝑚3 of that liquid has a mass of 34.8g. 5. What volume of ethyl alcohol has a weight of 125.0g. The specific gravity of alcohol is 0.791.
- 7. Seatwork #1 – June 11, 2014 1. Find the mass and weight of the air in a living room with a 4.00m x 5.00m floor and a ceiling of 3.00m high. What is the mass and weight of an equal volume of water? 2. The mattress of water bed is 2.00m long by 2.00m wide and 3.0cm deep. Find the weight of the water in the mattress. 3. You purchase a rectangular piece of metal that has dimensions 5.0mm x 15.0mm x 3.00mm and a mass of 0.0158kg. The seller tells you that the metal is gold. To check this, you compute the average density of the piece. What value do you get? Were you cheated?