# Mass - 8th grade (13y) - examples

- Iron ball

The iron ball has a weight of 100 kilograms. Calculate the volume, radius, and surface if the iron's density is h = 7.6g/cm^{3}. - Acid evaporation

How many kilograms of water do we have to evaporate from 100 kg of 32% acid to make it 80% concentration? - Car crash

After a traffic accident, police measured 1.16 permille of alcohol in the driver's blood. What amount of alcohol did the driver have in the blood when about 5 kg of blood circulates in the human body? - Beer

After three 10° beers consumed in a short time there are 5.6 g of alcohol in 6 kg adult human blood. How much is it per mille? - Coffee

In stock are three kinds of branded coffee prices: I. kind......248 Kč/kg II. kind......134 Kč/kg III. kind.....270 Kč/kg Mixing these three species in the ratio 10:7:7 create a mixture. What will be the price of 1100 grams of this mixture? - Sphere

Surface of the sphere is 2820 cm^{2}, weight is 71 kg. What is its density? - Vinegar 2

How many percentage of getvinegar solution, if we mix to 2 liters of 5.9% and 2 liters of 3.5% vinegar? - Eiffel Tower

Eiffel Tower in Paris is 300 meters high, is made of steel. Its weight is 8000 tons. How tall is the tower model made of the same material, if it weigh is 2.4 kg? - Alcohol

How many 55% alcohol we need to pour into 14 liters 75% alcohol to get p3% of the alcohol? How many 65% alcohol we get? - Density - simple example

Material of density of 762 kg/m^{3}occupies a container volume of 99 cm^{3}. What is its mass? - Barrel of oil

Barrel of oil weighs 283 kg. When it mold 26% oil, weighed 216 kg. What is the mass of the empty barrel? - Tare

Gross weight of shipment is 5188 kg and its tare is 5.6%. Calculate the net weight of the shipment. - Cu thief

The thief stole 122 meters copper wire with cross-section area of 95 mm^{2}. Calculate how much money gets in the scrap redemption, if redeemed copper for 5.5 eur/kg? The density of copper is 8.96 t/m^{3}. - Sea water

Mixing 34 kg of sea water with 34 kg rainwater is created water containing 3.4% salt. How many percent sea water contains salt? - Air mass

What is the weight of the air in a classroom with dimensions 10 m × 0 m × 2.5 m ? The air density is 1.293 kg/m^{3}. - Plastic pipe

Calculate weight of the plastic pipe with diameter d = 70 mm and length 380 cm if the wall thickness is 4 mm and the density of plastic is 1367 kg/m^{3}. - Pump

What power has a pump output to move 4853 hl of water to a height of 31 m for 8 hours? - Hollow sphere

Calculate the weight of a hollow tungsten sphere (density 19.3 g/cm^{3}), if the inner diameter is 14 cm and wall thickness is 3 mm. - Pizza

Pizza with a diameter 50 cm have weight 559 g. What diameter will have a pizza weighing 855 g if it is make from the same cloth (same thickness....) and same decorated? - Cube

The cube weighs 24 kg. How weight is cube of the same material, if its dimensions are 2-times smaller?

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