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Google AdSense is a program run by Google that allows publishers in the Google Network of content sites to serve automatic text, image, video, or ... more

Profit margin, net margin, net profit margin or net profit ratio all refer to a measure of profitability. It is calculated by finding the net profit as a ... more

In finance, leverage is a general term for any technique to multiply gains and losses. Operating leverage is an attempt to estimate the percentage change ... more

Profit margin, net margin, net profit margin or net profit ratio all refer to a measure of profitability. It is calculated by finding the net profit as a ... more

In accounting and finance, earnings before interest and taxes (EBIT), is a measure of a firm’s profit that includes all ... more

n financial accounting, an asset is an economic resource. Anything tangible or intangible that is capable of being owned or controlled to produce value and ... more

Compound annual growth rate is a business and investing specific term for the geometric progression ratio that provides a constant rate of return over the ... more

In financial accounting, an asset is an economic resource. Anything tangible or intangible that is capable of being owned or controlled to produce value ... more

In financial accounting, an asset is an economic resource. Anything tangible or intangible that is capable of being owned or controlled to produce value ... more

In finance, leverage is a general term for any technique to multiply gains and losses. Financial leverage tries to estimate the percentage change in net ... more

where **t** is the total consumption time, **t _{d}** is the days of consumption and

**t**the hours of consumption per day

_{h}where **P** is Power consumption rate, **E** is the energy supplied by the electricity company and **t** is consumption time

keywords:

ballistics

where **C** is the total cost and **C _{kW}** is the cost per kilowatt hour

Reference : OpenStax College,College Physics. OpenStax College. 21 June 2012.

http://openstaxcollege.org/textbooks/college-physics

Creative Commons License : http://creativecommons.org/licenses/by/3.0/

Days in inventory is an efficiency ratio that measures the average number of days the company holds its inventory before selling it. Cost of goods sold or ... more

The cost of capital is a term used in the field of financial investment to refer to the cost of a company’s funds (both debt and equity). Equity is ... more

In aerospace engineering, mass ratio is a measure of the efficiency of a rocket. It describes how much more massive the vehicle is with propellant than ... more

The weighted average cost of capital is the rate that a company is expected to pay on average to all its security holders to finance its assets. It is the ... more

The dividend discount model is a method of valuing a company’s stock price based on the theory that its stock is worth the sum of all of its future ... more

Earnings per share is the monetary value of earnings per each outstanding share of a company’s common stock. In business, net income – also ... more

Profit percentage is the percentage of cost price that one gets as profit on top of cost price. Profit percentage is calculated with cost price taken as ... more

Earned value management (EVM), earned value project management, or earned value performance management (... more

Earned value management (EVM), earned value project management, or earned value performance management (... more

Earned value management (EVM), earned value project management, or earned value performance management (... more

In finance, leverage is a general term for any technique to multiply gains and losses. Most often it involves buying more of an asset by using borrowed ... more

Trip distribution (or destination choice or zonal interchange analysis) is the second component (after trip generation, but before mode choice and route ... more

Trip distribution (or destination choice or zonal interchange analysis) is the second component (after trip generation, but before mode choice and route ... more

A typical small rescue helicopter, like the one in the Figure below, has four blades, each is **4.00 m** long and has a mass of **50.0 kg**. The blades can be approximated as thin rods that rotate about one end of an axis perpendicular to their length. The helicopter has a total loaded mass of **1000 kg**. **(a)** Calculate the rotational kinetic energy in the blades when they rotate at **300 rpm**. **(b)** Calculate the translational kinetic energy of the helicopter when it flies at **20.0 m/s**, and compare it with the rotational energy in the blades. **(c)** To what height could the helicopter be raised if all of the rotational kinetic energy could be used to lift it?

The first image shows how helicopters store large amounts of rotational kinetic energy in their blades. This energy must be put into the blades before takeoff and maintained until the end of the flight. The engines do not have enough power to simultaneously provide lift and put significant rotational energy into the blades.

The second image shows a helicopter from the Auckland Westpac Rescue Helicopter Service. Over 50,000 lives have been saved since its operations beginning in 1973. Here, a water rescue operation is shown. (credit: 111 Emergency, Flickr)

Strategy

Rotational and translational kinetic energies can be calculated from their definitions. The last part of the problem relates to the idea that energy can change form, in this case from rotational kinetic energy to gravitational potential energy.

Solution for **(a)**

We must convert the angular velocity to radians per second and calculate the moment of inertia before we can find **E _{r}** . The angular velocity

**Ď‰**for

**1 r.p.m**is

and for **300 r.p.m**

The moment of inertia of one blade will be that of a thin rod rotated about its end.

The total I is four times this moment of inertia, because there are four blades. Thus,

and so The rotational kinetic energy is

Solution for **(b)**

Translational kinetic energy is defined as

To compare kinetic energies, we take the ratio of translational kinetic energy to rotational kinetic energy. This ratio is

Solution for **(c)**

At the maximum height, all rotational kinetic energy will have been converted to gravitational energy. To find this height, we equate those two energies:

Discussion

The ratio of translational energy to rotational kinetic energy is only **0.380**. This ratio tells us that most of the kinetic energy of the helicopter is in its spinning bladesâ€”something you probably would not suspect. The **53.7 m** height to which the helicopter could be raised with the rotational kinetic energy is also impressive, again emphasizing the amount of rotational kinetic energy in the blades.

Reference : OpenStax College,College Physics. OpenStax College. 21 June 2012.

http://openstaxcollege.org/textbooks/college-physics

Creative Commons License : http://creativecommons.org/licenses/by/3.0/

Trip distribution (or destination choice or zonal interchange analysis) is the second component (after trip generation, but before mode choice and route ... more

In finance, leverage is a general term for any technique to multiply gains and losses.Most often it involves buying more of an asset by using borrowed ... more

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