Time + energy - practice problems - page 3 of 4
Number of problems found: 68
- 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 of 50 m? - 3 phase load
Two wattmeters are connected to measure power in a 3 phase balanced load. Determine the total power and power factor if the two wattmeters read 1000 watts each (1) both positive and (2) the second reading is negative. - Kilowatt-hours
If the Lewis family used 648 kilowatt-hours of electricity in 12 days, how many kilowatt-hours should they use in 24 days at the same usage rate? - 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? - Workers 7767
Twelve workers would earn € 800 in 10 days. How many euros would 14 workers earn in 8 days? - Performance 7737
Zdenek, weighing 54 kg, made 15 push-ups on the crossbar. The height he reached was about 40 cm. What kind of work did he do? What was his performance if the whole exercise took him a minute and a half? - Temperature 7595
Colorless liquid weighing m = 200 g is heated with constant stirring on a stove with power input P0 = 600W. 80% of the supplied energy is used to heat the liquid. Selected measured values of liquid temperature as a function of time are recorded in the t - Temperature 7477
The pool with a length of l = 50 m and a width of s = 15 m has a depth of h1 = 1.2 m at the shallowest part of the wall. The depth then gradually increases to a depth of h2 = 1.5 m in the middle of the pool. = 4.5 m walls in the deepest part of the pool.
- 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 m3/s is supplied with a flow rate of h = 70.5 m at full power. a) What is the total installed pow - Refrigerator 6703
Calculate how much we will pay for 1 hour of consumed electrical energy if the seller sets a price of 0.126 euros for 1 kWh (all appliances together for 1 hour of work). Table: Appliance Power (W) Washing machine 2300 W Bulb 40W Refrigerator 200W TV 110W - Bulbs and electricity
In the sports hall, 875 identical light bulbs light for 2 hours. How long do 100 such light bulbs consume the same amount of electricity? - Electricity 6667
A light bulb with power consumption P = 70 W. It is connected to a mains voltage of 230 V. How big is the electric current that flows through it? How much electricity in kWh will it use if it is on for 9 hours 30 minutes? - Consumption 6581
We heated water weighing 1 kg at 70 degrees in a kettle. C. In 5 min. What is the power consumption of the kettle? We do not take into account losses or boiling points.
- Electric energy
There are 875 identical light bulbs in the sports hall lighting for 2 hours. How long does the same amount of electricity consume 100 such bulbs? - Bulb
A 60 W bulb consumes 0.12 kWh of electricity. How long did she stand light without a break? - Granddaughter 4237
Mrs. Helena has an old cell phone with nothing to do but makes phone calls. The cell phone will discharge in 72 hours when fully charged and on the phone. Three hours of calling in a row are enough to discharge a fully charged phone. After the last full c - Efficiency 4072
What kind of work did the mixer with an efficiency of 30% do when it did 4.5 kWh of work? - Fuel mileage
You have 3/8 tank of fuel. Estimate fuel consumption @ 6mpg. Estimate speed @ 50mph. Your fuel tank holds 200 gals. Figure out fuel mileage.
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