# Power - practice problems

Power is the amount of work done (energy supplied) per unit time. In physics, power is the amount of energy transferred or converted per unit time. In the SI units, the unit of power is the watt, equal to one joule per second. Other units are, for example, 1 hp (one horsepower; 1 hp = 735.5 W) and then derived units such as kW - kilowatt.#### Number of problems found: 294

- An architect 2

An architect is designing a house. He wants the bedroom to have the dimensions of 8 ft by 4 ft by 7 ft. The architect doubles all three dimensions to create the den. Does that mean the den will have double the volume of the bedroom? First, find the volume - Two gardens

The flower garden has a square shape. The new garden has the shape of a rectangle, and one dimension is 8 m smaller, and the other is twice as large as in a square garden. What were the original garden dimensions and the new garden if both gardens' area i - Future value investment

Poseidon deposited 2,747 golden drachmas in a Mount Olympus college savings account to ensure Percy can go to college. It pays 0.04 (percent in decimal form) annual interest. After 11 years, he withdraws the money. How much more money would he have if the - The output

The output voltage of the transformer is 880 V. The secondary coil has 1200 turns. Find the voltage to which the primary coil is connected and how many turns it has if a current of 1 A flows through it. Transformation ratio k = 4. What current flows throu - Free fall

The elevator car weighing 720 kg is torn off at a height of 125 m and begins to fall in a free fall. How much kinetic energy does the elevator car have when it hits the ground floor of the building, when the free fall of the car lasted 5 s? - The length 2

The length of a rectangle is 12y² – 15y + 8 and the width is 7y – 11. Find the area of the rectangle - Circuit voltage

Calculate the closed-circuit voltage. Calculate the power on the resistors. R1 = 30 ohms, R2 = 10 ohms. I = 0.1A. U =?. The resistors are connected in series, one after the other. - The sum

The sum of the squares of two immediately following natural numbers is 1201. Find these numbers. - Cube-shaped box

The cube-shaped box is filled to the brim with 2 liters of milk. Calculate the edge and surface of the box. - Three cubes

Two cube-shaped boxes with edges a = 70 cm; b = 90 cm must be replaced by one cube-shaped box. What will be its edge? - What is 10

What is the measure of the square side whose area is (4x² + 28x+49) square units? - Granddaughter

In 2014, the sum of the ages of Meghan's aunt, her daughter and her granddaughter was equal to 100 years. In what year was the granddaughter born, if we know that the age of each can be expressed as the power of two? - 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 - Find x 2

Find x, y, and z such that x³+y³+z³=k, for each k from 1 to 100. Write down the number of solutions. - Present value

A bank loans a family $90,000 at 4.5% annual interest rate to purchase a house. The family agrees to pay the loan off by making monthly payments over a 15 year period. How much should the monthly payment be in order to pay off the debt in 15 years? - Future value

Suppose you invested $1000 per quarter over a 15 years period. If money earns an anual rate of 6.5% compounded quarterly, how much would be available at the end of the time period? How much is the interest earn? - The cube

The cube has a surface of 600 cm². What is its volume? - Sum of GP members

Determine the sum of the GP 30, 6, 1.2, to 5 terms. What is the sum of all terms (to infinity)? - What is 10

What is the 5th term, if the 8th term is 80 and common ratio r =1/2? - What are 2

What are the two more terms of the GP a, ax, ax^{2}, ax^{3}, __, __?

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