In homes with more floor elevators are used. For passenger transport, the most commonly used traction elevator counterweight. The top of the shaft
engine room with the engine. The car is suspended on a rope, which is guided up over two pulleys to the counterweight.

Consider lift-enabled load Mmax = 300 kg
car weight mk = 500 kg
weight counterweight mz = 650 kg. Cabin moves at the speed
v0 = 1.2 m/s. The total efficiency of power is k =75%.

a) Explain what affects the efficiency of the system and the reason for using a counterweight.

b) Determine the power P1 engine lift if you summon an empty cabin residents of the upper floors, which moves down the speed of v0.
c) Determine the power P2 engine lift when a group of citizens with a total mass M = 250 kg conveys speed v0 upwards.

In which of these cases b), c) the need for more power?
g = gravitational constant 10 N/kg


P1 =  2.4 kW
P2 =  1.6 kW


P1=mkmzgv010075 P1=500650101.210075=2.4 kWP_1 = |m_k-m_z|g v_0 \dfrac{ 100 }{ 75 } \ \\ P_1 = |500-650| 10 \cdot 1.2 \dfrac{ 100 }{ 75 } = 2.4 \ \text{kW}
P2=mk+Mmzgv010075 P2=500+250650101.210075=1.6 kW P1>P2P_2 = |m_k+M-m_z|g v_0 \dfrac{ 100 }{ 75 } \ \\ P_2 = |500+250-650| 10 \cdot 1.2 \dfrac{ 100 }{ 75 } = 1.6 \ \text{kW} \ \\ P_1 > P_2

Our examples were largely sent or created by pupils and students themselves. Therefore, we would be pleased if you could send us any errors you found, spelling mistakes, or rephasing the example. Thank you!

Leave us a comment of this math problem and its solution (i.e. if it is still somewhat unclear...):

Showing 0 comments:
1st comment
Be the first to comment!

Tips to related online calculators
Our percentage calculator will help you quickly calculate various typical tasks with percentages.
Do you want to convert velocity (speed) units?
Do you want to convert time units like minutes to seconds?

You need to know the following knowledge to solve this word math problem:

Next similar math problems:

  1. Shot
    wood_projectile Shot with a mass 43 g flying at 256 m/s penetrates into the wood to a depth 25 cm. What is the average force of resistance of wood?
  2. Researchers
    house Researchers ask 200 families whether or not they were the homeowner and how many cars they had. Their response was homeowner: 14 no car or one car, two or more cars 86, not homeowner: 38 no car or one car, two or more cars 62. What percent of the families
  3. Profit gain
    percent_12 If 5% more is gained by selling an article for Rs. 350 than by selling it for Rs. 340, the cost of the article is:
  4. The farm
    kombajn The farm harvested 390 tons of grain. Wheat was 15% more than barley, and rye was 126 tons less than wheat and barley combined. How many tons of wheat, how many tons of barley, and how much rye did the team get?
  5. Vegan shop
    zemiaky_2 To the shops brought together 23.2 kg of goods, fruits, vegetables and nuts. fruit was 4.7 kg more than vegetables, nuts was 1.5 kg less than the fruit. Determine the amount of fruits, vegetables and nuts.
  6. Lee is
    clock-night-schr_15 Lee is 8 years more than twice Park's age, 4 years ago, Lee was three times as old. How old was Lee 4 years ago?
  7. Speedometer
    lotus The speedometer of a car reads 66 km/h. It's accurate to within 4.1% What is the maximum possible error?
  8. Theorem prove
    thales_1 We want to prove the sentence: If the natural number n is divisible by six, then n is divisible by three. From what assumption we started?
  9. Christmas holidays
    christmas How many percent take Christmas holidays lasting 18 days from a school year that lasts 303 days? Round the result to two decimal places
  10. Summerjob
    tree2 The temporary workers planted new trees. Of the total number of 500 seedlings, they managed to plant 426. How many percents did they meet the daily planting limit?
  11. A particle
    integral_speed A particle moves in a straight line so that its velocity (m/s) at time t seconds is given by v(t) = 3t2-4t-4, t>0. Initially the particle is 8 meters to the right of a fixed origin. After how many seconds is the particle at the origin?
  12. G forces
    car_crash Calculate deceleration of car (as multiple of gravitational acceleration g = 9.81 m/s2) which occurs when a car in a frontal collision slows down uniformly from a speed 111 km/h to 0 km/h in 1.2 meters trajectory.
  13. Friction coefficient
    car 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
  14. Pooja
    clocks_14 Pooja and Deepa age is 4:5, 4 years back it was 8:11. What is the age of Pooja now?
  15. Family
    4kids Family has 4 children. Ondra is 3 years older than Matthew and Karlos 5 years older than the youngest Jane. We know that they are together 30 years and 3 years ago they were together 19 years. Determine how old the children are.
  16. Apple variete
    jablka This year, my uncle harvested 350 kg of apples, including 105 kilograms of Ontario, and the rest is Jonathan. Determine what percentage of the Jonathan apples.
  17. Simple interest 3
    coins-uk_1 Find the simple interest if 11928 USD at 2% for 10 weeks.