Mass - 9th grade (14y) - math problems

Number of problems found: 218

  • Ice to boiling water
    ice_cubes Calculate the heat needed to convert 5kg of ice with a temperature of -5°C to water with a temperature of 100°C. c (water) = 4200 J. Kg-1. kg-1, c (ice) = 2100 J. Kg-1. kg-1. the mass group heat of solidification of water is l = 334kJ/kg. Calculate the he
  • Salt solution
    Salt-Sodium-Chloride-NaCl Calculate the weight of a 50% salt solution that we prepare from 120 g of salt.
  • Beef taxation
    maso How much should the price of 2.5 kg of beef change, which in December cost € 5.71 per 1 kg if VAT changed from 20% to 10%. how much will 2.5kg cost from January?
  • Shen's
    cokolada Shen's chocolate bar is 54% cocoa. If the weight of the chocolate bar is 54 grams, how many grams of cocoa does it contain? Round your answer to the nearest tenth.
  • Dynamometer
    archimedes2 What is the volume of a body that stretches a dynamometer in air, on which it is suspended by a force of 2.5 N, and if it is immersed in alcohol with a density of 800 kg/m ^ 3, does it tension the dynamometer with a force of 1.3 N?
  • Above water surface
    archimedes If we remove the stone from the water, we apply a force of 120N. How much force will we have to exert if we move the stone above the water surface? The density of the stone is 5000 kg/m ^ 3.
  • Bottle, cup and jug
    flasa The bottle and the cup have the same weight as the jug. The bottle has the same weight as the cup and plate. Two jugs have the same weight as three plates. What is the weight of the bottle, if the weight of the cup is 100g.
  • There
    watermixing There is 5 l of water with a temperature of 20°C in the bucket. We add 3 liters of hot water. The resulting temperature will be 30°C. What was the temperature of the hot water?
  • Feed to hay
    luka How many tons of water do we have to dehydrate from 8 tons of feed, if the original moisture is 54 percent, to get hay with a moisture content of 15 percent? Round to two decimal places.
  • School model
    jehlan_4b_obdelnik The beech school model of a regular quadrilateral pyramid has a base 20 cm long and 24 cm high. Calculate a) the surface of the pyramid in square decimeters, b) the mass of the pyramid in kilograms if the density of the beech is ρ = 0,8 g/cm ^ 3
  • Latent heat
    ice How much heat is needed to take from 100 g of water at 20°C to cool to ice at -18°C? Mass heat capacity c (ice) = 21kJ/kg / °C; c (water) = 4.19 KJ/kg / °C and the mass group heat of solidification of water is l = 334kJ/kg
  • Heat transfer
    sphere_Nickel We placed a lead object weighing 0.4 kg and 250°C in 0.4 L water. What was the initial temperature of water t2 if the object's temperature and the water after reaching equilibrium was 35°C? We assume that the heat exchange occurred only between the lead o
  • A semi-circular
    fishbowl A semi-circular fishbowl is filled with water and has a diameter of 10 feet. What is the total weigh of water to the nearest pound in the tank, if water weighs 62.5 pounds per cubic foot?
  • Two boys
    korcule Two boys weighing 60kg and 90kg move on roller skates and are attracted to each other by a rope. One boy exerts a force of 15N. What force does the other boy exert? What accelerations will the boys gain? Do not consider friction or air resistance.
  • The square
    woord The square oak board (with density ρ = 700 kg/m3) has a side length of 50 cm and a thickness of 30 mm. 4 holes with a diameter of 40 mm are drilled into the board. What is the weight of the board?
  • The aluminum
    sphere_Nickel The aluminum object with a weight of 0.80 kg and a temperature of 250°C was placed in the water with a weight of 1.6 kg and a temperature of 23°C. What is the system temperature after reaching equilibrium? We assume that the heat exchange occurred only be
  • The bath
    watermixing The bath has water with a volume of 220 l and a temperature of 65°C. Determine the mass m2 of water at 15°C to be poured so that the resulting temperature of the water in the bath is 40°C. We neglect the heat exchange between water and the environment. T
  • Ten apples
    average The average weight of ten apples is 200 g. How does the average weight of apples change if we eat one apple weighing 129 g?
  • Six hens
    chicken Six hens weigh 3 kg more than three geese and 7 kg less than five geese. How much does a hen weigh, and how many geese?
  • Average weight
    apples Mom bought 6 apples with an average weight of 130 g - If she took 1 apple out of the bag, the average weight of the remaining apples changed to 140 g. What was the weight of the removed apple?

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Mass - math problems. Examples for 9th grade.