PHYSICS MIDDLE SCHOOL

What is the definition of mechanical energy

Answers

Answer 1
Answer:

Mechanical energy is the sum of an object's kinetic and potential energy.


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MIDDLE SCHOOL

Match the simple machine with the correct definition. 1.___pulley                                                                
2.___wedge
3.___first- class lever
4.___screw
5.___Inclinded plane
6.___second- class lever
7.___wheel and axle
8.___lever
9.___third- class lever


A. any slanting, flat surface
B. a rigid bar that rotates about a pivot called a fulcrum
C. an inclined plane wrapped around a cylinder
D. load is in the middle
E. two inclined planes placed back to back
F. a wheel turning around an axle inserted through its center
G. effort is in the middle
H. a circular lever that consists of a grooved wheel rotating about a hub
I. fulcrum is between the effort and load

Answers


A. any slanting, flat surface is an inclinded plane

B. a rigid bar that rotates about a pivot called a fulcrum is a lever

C. an inclined plane wrapped around a cylinder is a screw

D. load is in the middle of a second class lever

E. two inclined planes placed back to back form a wedge

F. a wheel turning around an axle inserted through its center
is cleverly labeled a "wheel and axle".

G. effort is in the middle of a third class lever

H. a circular lever that consists of a grooved wheel rotating
about a hub is a pulley

I. fulcrum is between the effort and load of a first class lever


MIDDLE SCHOOL

An infant galaxy that is studied through the use of radio waves? galaxy
spiral
elliptical
irregular
quasar

Answers

An infant galaxy that is studied through the use of radio waves is called QUASAR.
Quasar are astronomical object, which have very high luminosity and they are found in the centers of some galaxies. Scientists believed that quasar are centers of distant galaxies. Radio waves is used to study quasar because they emit a huge amount of radio waves. 
HIGH SCHOOL

What is total internal reflection? When does it occur?

Answers

Answer:

Total internal reflection is the phenomenon that occurs when a ray of light travels from a medium of high refractive index to a lower refractive index medium.

In this sense, the ray is refracted in such a way that it is not able to cross the surface between both media, being completely reflected.

This is the physical principle used in optical fiber to conduct light through the fiber without energy loss.

It is important to note, that this phenomenon occurs at a limit angle , which is calculated from Snell's law, substituting the angle of the second medium by :

Where and are the refractive indexes of both media.

COLLEGE

What is the hypothesis for what effect does food color have on the amount of food fish eat

Answers

Absolutely none. Fish take food into their mouths and taste it. If they like it, they swallow, if not they will spit it out. The colour of the flakes has no bearing on what the fish takes in and tastes in my experience.
MIDDLE SCHOOL

PLEASE ANSWER BOTH IF YOU CAN, I NEED THESE ASAP!! 1. Compare the effects of a solar and lunar eclipse.

2. What obstacles prevent scientists from sending humans to Mars?

Answers

Solar eclipse: when the sun, moon, and earth align
Lunar eclipse: when the moon blocks the sun's light

1, there is no water there, so plants cant grow
2, there are no plants, hence, there would be no oxygen.
3, (not sure) the temperature is different from earth and could possible not sustain life
MIDDLE SCHOOL

A cannon fired horizontally at 20 m/s from the top of a cliff lands 80m away. how tall is the cliff

Answers

Answer:

The height of the cliff is, h = 78.4 m

Explanation:

Given,

The horizontal velocity of the projectile, Vx = 20 m/s

The range of the projectile, s = 80 m

The projectile projected from a height is given by the formula

                            S = Vx [Vy + √(Vy² + 2gh)] / g

Therefore,  

                            h = S²g/2Vx²

Substituting the values

                             h = 80² x 9.8/ (2 x 20²)

                                = 78.4 m

Hence, the height of the cliff is, h = 78.4 m

HIGH SCHOOL

Why do we believe that most of the mass of the Milky Way is in the form of dark matter?a. Although dark matter emits no visible light, we have detected its radio emissions.b. The orbital speeds of stars far from the galactic center are surprisingly high.c. Theoretical models of galaxy formation suggest that a galaxy cannot form unless it has at least 10 times as much matter as we see in the Milky Way disk.d. Our view of distant galaxies is often obscured by dark blotches, which are presumably made of dark matter.

Answers

Answer: The orbital speeds of stars far from the galactic center are surprisingly high.

Dark matter is a type of matter, whose composition is unknown and which corresponds to 80% of the matter in the universe. Its name refers to the fact it does not emit or interact with any type of electromagnetic radiation, being completely transparent throughout the electromagnetic spectrum.  

However, it interacts with the known matter through gravity.  

In this sense, it is believed that the Milky Way has 90% dark matter and only 10% ordinary matter (known matter). Because, like gravity, dark matter can not be observed directly, however its existence is inferred through the movement of the stars far from the center and the cosmic dust within the galaxy.

HIGH SCHOOL

What provides the force on the person on the passenger seat?

Answers


When the car speeds up, slows down, or goes around a curve,
passengers need a force applied to them to make them do the
same thing, otherwise they won't keep up with the car. 

The force on the passenger is applied by means of friction between
the upholstery and the seat of his pants, and also by the seat-back
or his seat-belt.

What do u mean? Do you mean what allows you to let you sit on the passengers seat?


HIGH SCHOOL

A ray of light passes from air into carbon disulfide (n = 1.63) at an angle of 28.0 degrees to the normal. what is the refracted angle?

Answers

We can solve the problem by using Snell's law, which states 

where
is the refractive index of the first medium
is the angle of incidence
is the refractive index of the second medium
is the angle of refraction

In our problem,  (refractive index of air),  and  (refractive index of carbon disulfide), therefore we can re-arrange the previous equation to calculate the angle of refraction:

From which we find

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