# Energy + mass - practice problems

#### Number of problems found: 25

- Ice to boiling water

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 - Lead melt

Find the heat needed to melt an object made of lead weighing 250g and an initial temperature of 35°C. Lead melts at 327°C at normal pressure. Mass heat capacity of lead c = 129 J/kg • K and mass latent heat of lead lt (t is the subscript) = 22.6 kJ/kg - There

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? - Latent heat

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 - The aluminum

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

The bath has water with a volume of 220 l and a temperature of 65°C. Determine the mass m_{2}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 envi - Electric cooker

During which time t does an electric cooker with power input P = 500 W and with efficiency n = 75% heat water with mass m = 2 kg and temperature t1 = 10°C to the boiling point (t2 = 100°C). The specific heat capacity of water is c = 4 180 J. Kg-1. K-1 - Harmonic oscillator

Calculate the total energy of a body performing a harmonic oscillating motion if its mass is 200 g, the amplitude of the deflection is 2 cm and the frequency is 5 Hz. Round the result to 3 decimal places. - Concrete column

The concrete column of the highway bridge has the shape of a block with dimensions of 1m x 0.8m x 25m. It should be lifted by crane to a height of 20m. What is the power of his engine if the lifting takes 2 minutes? - Receiving heat

How many degrees Celsius was an iron cylinder weighing 300 g heated in a water bath if it received heat of 7.2 kJ? (specific heat capacity of iron c = 0.46kJ/kg / ºC) - Inclined plane

1. How much work W we have to do to pull a body weighing 200 kg along an inclined plane with a length of 4 m to a total height of 1.5 m. 2. Find the force we need to exert to do this if we neglect frictional resistance. 3. Find the force we would need if - The elevator

The elevator car weighing 400 kg rises from the third to the fifth floor. By what value will the potential gravitational energy of the cabin increase? What useful work will the elevator motor do? The height of one floor is 5m . - Positional energy

What velocity in km/h must a body weighing 60 kg have for its kinetic energy to be the same as its positional energy at the height 50 m? - Friction coefficient

What is the weight of a car when it moves on a horizontal road at a speed of v = 50 km/h at engine power P = 7 kW? The friction coefficient is 0.07 - Power input

The construction lift lifted a load weighing 300 kg to a height of 12 m with a uniform movement. How long has it taken for the load to be lifted if the efficiency is 75% and the engine has a power input of 5 kW? - Orlík hydroelectric plant

The Orlík hydroelectric power plant, built in 1954-1961, consists of four Kaplan turbines. For each of them, the water with a flow rate of Q = 150 m^{3}/s is supplied with a flow rate of h = 70.5 m at full power. a) What is the total installed pow - A steel

A steel hammer with a weight of 0.5 kg hits the nail at a speed of 3 m/s. How deep the nail penetrates the wood if the hammer acts on the nail with an average force of 50N. - Chocolate roll

The cube of 5 cm chocolate roll weighs 30 g. How many calories will contain the same chocolate roller of a prism shape with a length of 0.5 m whose cross-section is an isosceles trapezoid with bases 25 and 13 cm and legs 10 cm? You know that 100 g of this - Water temperatures

To 25 liters of water at 50 °C we add 15 liters of water at a different temperature. How many °C should the water be colder than 50 °C so that 40 liters of the water obtained has a temperature 42.5 °C? - Cows

20 cows has food for 60 days. We reduce the dose to two-thirds for 18 cows. How many days will be fed?

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Energy - practice problems. Mass - practice problems.