2. top of the food chain

3. eats other animals that can be food for humans

4. no apparent use to humans.

Lions and tigers come in this category. They do not seem to have any particular use to the humans. We could keep a few in...

Killing all the lions and tigers...]]>

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principle of moments

Okay so when resolving the forces horizontally and vertically, I get R

Proving tension in rope of equilibrium system]]>

But when I imagine a signal being sent its like a squiggily wave, so what method does the reciever use to approximate the instantanious values of the signal into a mathematical...

What method does a reciever or transmitter use to approx...]]>

Does a compressed spring create work?]]>

Unitary evolution of coupled systems results in entanglement and thus an improper...

Is there an interpretation independent outcome problem?]]>

Infinite at big bang?]]>

At the moment CNN is reporting

"Tickets linked to stolen passports for missing Malaysia flight were purchased by Iranian man,...

Malaysia Airlines Flight 370 crash]]>

Earth's Rotation and Atmosphere]]>

Questions about density and being in the air]]>

"An ultrasonic field will be a combination of standing and travelling waves. An increase in the traveling wave will decrease the proportion of a standing wave and vica versa".

I'm trying to visualise this, I understand the...

Can a sound wave be both standing and traveling?]]>

A pilot is flying from City A to City B which is 300 km [NW]. If the plane will encounter a constant wind of 80 km/h from the north and the schedule insists that he complete his trip in 0.75 h, what air speed and heading should...

Kinematics Question]]>

So I'm going through a chapter on dual spaces and I came across this:

"A key property of any dual vector ##f## is that it is entirely determined by its values on basis vectors.

## f_i \equiv f(e_i) ##

which we refer to as the components of ##f## in the basis ##{e_i}##, this is...

Components of a dual vector?]]>

Understanding the General Relativity View of Gravity on Earth...

Understanding the General Relativity view of gravity on Earth - Comments]]>

Thermal Expansion of Two Holes]]>

I wondered about the plausibility of the...

Underground biosphere, what can be the possibilities?]]>

How to explain this?]]>

Is this true for higher dimensional surfaces as well?

Would a three-dimensional surface, with everywhere positive curvature be a closed hypersurface isomorphic to a...

Curvature implying Closedness in N dimensions]]>

Hi, everyone.

my teacher stuck me with these questions and i am need of a little help answering question 2.

here's my answers to question 1 first.

1a) a=0, as system would...

pulley question]]>

I have been...

At what point has the oil gone bad?]]>

A high voltage powerline operates at a 500000 V-rms and carries an rms current of 500 A. If the resistance of the cable is 0.05Ω/km, what is the resistive power loss in 200 km of the powerline.

V = 500000 V-rms

I

Physics E & M Question about a powerline]]>

Two moving objects (circle shaped) with a known mass, move in a 2D plane with a known constant direction and speed, at certain point, objects collide with eachother (elastic). At that point, the coordinates of the...

Two-Dimensional Collision With Two Moving Objects]]>

Square steel tubing for a beam...did I do this right?]]>

Understanding Entropy and the 2nd Law of Thermodynamics...

Understanding Entropy and the 2nd Law of Thermodynamics - comments]]>

Given: Wheel radius is 20 CM, Gear radius is 5 CM, Coefficient of Static Friction is .2, Weight on rear wheel is 50 N.

What is the minimum force that must be applied to the pedal for the wheel to begin accelerating on a level...

Bicycle Translational Acceleration vs Angular Acceleration]]>

Introduction to relativistic quantum mechanics and maybe QFT]]>

1. The problem statement, all variables and given/known data

Let S be a subset of a group G...

Show that a normal subgroup <S> is equal to <T>]]>

I am thinking about what know of machines in RF lab can catch heart beat signal,

In the RF lab with spectrum and network analyzers, also have Function generator and more.

They are just working on signal with high frequencies, but heart beats are very low frequencies about...

how can I catch heart beat signals?]]>

First of all, let me clarify that I love, LOVE ethnic cuisine and foods that are local to a particular region. I find that I learn a lot about groups of people or the local...

Your Local Cuisine]]>

I've known that saturation current occurs when V

For NPN transistor, electrons from emitter (majority carrier of emitter) is able to go up to only base, no further...

How we can physically imagine transistor saturation current?]]>

i heard bill gates wants to invest in traveling wave reactor.

to limit the field, it has to use uranium, must be economical, must produce very little waste, must be safe, and it can be built with current technology.

built in a...

what is the most promising gen 4 or 5 design?]]>

I am looking for the speed necessary to cause a specific g-force rating of 5.22 on an object weighing in at 11, 245 lbs and the distance covered would be approximately 1...

Calculate speed of object given g-force]]>

There are six people. They have various likes and dislikes for each other, which are asymmetric (as one...

Asymmetry question]]>

Writing CV for PhD application]]>

There are 7 different postbox, and 10 identical letters. How many ways can the letters put into the boxes so that there is at least one letter in a postbox?

nCr=n!/(n-r)!r!

If M,N,O..... things...

ways to put letters in postboxes]]>

Design a filter that will pass frequencies greater than 20 Hz and set the -3dB point at 10 Hz. Assume zero source impedance and 10k load impedance.

##f=\frac{1}{2\pi RC}## which is the equation...

Design of High-pass Passive Filter]]>

Is the following way a good one :

Parametrize a 3 sphere with $$\theta,\phi,\chi$$

Put $$\chi=f(\theta,\phi)$$

Does it make the manifold closed ?]]>

I've always been interested in other primates and other...

Do you think there are things forever beyond our grasp?]]>