Which two statements are true about a system?

a)A system is a group of objects analyzed as one unit.
b)Energy that moves across system boundaries is conserved.
c)There’s only one way to define the boundaries of a system.
d)All systems are made by humans.

Answers

Answer 1
A and c

Because it defines the boundaries of the system

Related Questions

A car has a mass of 2000 kg. While it is traveling along a perfectly flat road, it goes around an unbanked turn that has a radius of 40.0 m. The coefficient of static friction between the car tires and the road is 0.500. The car travels successfully around the turn at a constant speed of 10.0 m/s. Calculate the magnitude of the car's acceleration as it goes around the turn. _______ m/s^2

Answers

Answer:

2.5 m/s²

Explanation:

The given parameters are;

The mass of the car, m = 2,000 kg

The radius of the car, r = 40.0 m

The coefficient of friction between the car tires and the road, μ = 0.500

The constant speed with which the car moves, v = 10.0 m/s

The normal reaction of the road on the car, N = The weight of the car;

∴ N = m × g

Where;

g = The acceleration due to gravity ≈ 9.81 m/s²

N ≈ 2,000 kg × 9.81 m/s² = 19,620 N

The frictional force, [tex]F_f[/tex] = μ × N

The centripetal force, [tex]F_c[/tex] = m·v²/r

The car moves without slipping when [tex]F_f[/tex] = [tex]F_c[/tex]

Therefore, [tex]F_f[/tex] = 0.500 × 19,620 N = 2,000 kg × [tex]v_{max}[/tex]²/40.0 m

∴ [tex]v_{max}[/tex] = √(0.500 × 19,620 N × 40.0 m/2,000 kg) ≈ 14.007 m/s

Therefore, the velocity with which the car moves, v < [tex]v_{max}[/tex]

The cars centripetal acceleration, [tex]a_c[/tex] = v²/r

∴ [tex]a_c[/tex] = (10.0 m/s)²/40.0 m = 2.5 m/s²

The cars centripetal acceleration as it goes round the turn, [tex]a_c[/tex] = 2.5 m/s².

give one example where friction is a hindrance. ​

Answers

Answer:

an example of when friction is a hindrance, is if someone with shorts is sliding down a slide. their skin rubbing on the slide will cause friction and will slow them down. another example is if you're dragging a large wooden box across the floor. the wood and the floor interacting cause friction and will make it more difficult to push the box.

Explanation:

hope this helps :D

help me please i will mark as brainliest

Answers

Answer:

you would be paying $1845.26

An object moving north with an initial velocity of 14 m/s accelerates 5 m/s2 for 20 seconds. What is the final velocity of the object?
39 m/s
90 m/s
114 m/s
414 m/s

Answers

Answer:

option C

Explanation:

Final velocity of the object is 114 m / s. Hence, final velocity of the object is 114 m / s.

Here is the answer ! Hope it helps.

Which of the following best describes reverberation?
A.The wave fronts become mixed and broken up due to contact with a rough or
irregular surface.
B. A change in the sound wave velocity causes the wave to bend in a different
direction.
C. A fraction of the sound waves are absorbed by an object and converted to heat
energy.
D. A single sound undergoes several reflections due to multiple reflecting surfaces.

Answers

Reverberation, in psychoacoustics and acoustics, is a persistence of sound after the sound is produced

Explanation:

I think it is right hope its helps

Answer:

D. A single sound undergoes several reflections due to multiple reflecting surfaces.

Explanation:

Sometimes, the source of a sound is surrounded by multiple reflecting surfaces. The waves traveling from the source strike these different surfaces, causing multiple reflections. For example, a single clap of thunder reflects on several clouds and the earth's surface, causing you to hear a rolling rumble instead of a single sound.

A variable is a letter that stands in for a number and unit... True or False?

Answers

True it represent two or more numbers

Which type of reactions usually happens slowest?

Answers

Answer:

option b is correct..................

Invisible damage to the body resulting from repeating a movement often is a

Answers

Answer: repetitive strain injury


Explanation: The repetitive strain injury (RSI), also known as overuse syndrome, is defined as the invisible damage to the body resulting from repeating a movement. These type of damage can affect the muscles, nerves, ligaments and tendons.

What the suns mass in scientific notation????

Answers

Explanation:

In scientific notation the Sun's mass is: =1.989 x 10 ^30 kg

Answer:

I think in scientific notation the Sun's mass becomes: M Sun = 1.989 x 10 30 kg. The number above the ten, called the power of ten or exponent, stands for the number of decimal places. If it is positive, as in the mass of the Sun, the decimal places are in front of the decimal point.

I hope this help you!:)

Suppose that people living near a particular​ high-voltage power line have a higher incidence of cancer than people living farther from the power line. Can you conclude that the​ high-voltage power line is the cause of the elevated cancer​ rate? If​ not, what other explanations might there be for​ it? What other types of research would you like to see before you conclude that​ high-voltage power lines cause​ cancer?

Answers

Complete Question

Complete Question is attached below

Answer:

a)Option B

b)Option B

Explanation:

a)

Without any confirmation it will be utterly wrong to conclude that high power voltage is the reason for the elevated cancer cases

Therefore

Option B

b)

The High Concentration of cells volume in a part of the Body is what causes Cancer

Therefore

Option B

can someone please help me with a and b? what do they mean by amplitude?​

Answers

Explanation:

first answer is that the to and fro movement of a pendulum is known as amplitude

is noise energy a kind of energy or not

Answers

yes. sound waves are produced by energy.

Write down the role played by four digestive juices in digestion and the
organs which secrete them.

Answers

Answer:

Explanation:Digestive juices secreted by various organs such as salivary glands in the mouth, stomach, liver and pancreas help in the process of digestion of food. Saliva secreted by the salivary glands in the mouth aids in the breakdown of starch present in the food to simple sugar

Calculate the upthrust on a object immersed in water if the object displace water of mass 2 kg.(g=9.8m/s²) ​

Answers

Thrust is force

Mass=2kgAcceleration due to gravity=g=9.8m/s^2

Using Newtons Second law

[tex]\boxed{\sf Force=Mass\times Acceleration}[/tex]

[tex]\\ \qquad\quad\sf{:}\dashrightarrow Thrust=2(9.8)[/tex]

[tex]\\ \qquad\quad\sf{:}\dashrightarrow Thrust=19.6N[/tex]

We have that the the upthrust on a object immersed in water is

[tex]U=19.6N[/tex]

From the Question we are told that

mass= 2kg

Gravity g=9.8m/s^2

Generally the equation for the upthrust  is mathematically given as

[tex]U=mg[/tex]

Therefore

[tex]U=2*9.8[/tex]

[tex]U=19.6N[/tex]

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importance of estimation in our lives​

Answers

In real life, estimation is part of our everyday experience. For students, estimating is an important skill. First and foremost, we want students to be able to determine the reasonableness of their answer. Without estimation skills, students aren't able to determine if their answer is within a reasonable range.

what is the Ramsar convention?

Answers

The Ramsar Convention on Wetlands of International Importance Especially as Waterfowl Habitat is an international treaty for the conservation and sustainable use of wetlands.

........................

Answers

Answer:

14°F = 263.15 K

31°F = 272.594 K

71°F = 294.817 K

35°F = 274.817 K

Explanation:

Use the formula 273.15 + ((°F–32)•5)/9

A glass rod acquires charge by rubbing silk cloth. The charge on the glass is due to:
(a) Friction
(b) Conduction
(c) Induction
(d) Radiation

Answers

Answer:

(a)Friction

Explanation:

It is due to friction as you are rubbing the glass rod with silk cloth  

as friction occurs when 2 surfaces are rubbed against each other

Therefore it is charging by friction

Why do scientists not use US customary units when reporting their data?

Answers

One of the scientist's jobs is to report the results of his experiments to all the other scientists in the world.

There isn't a single real science shop anywhere in the world that uses the US customary system of units. Not one.

Even in the measly three countries that use it for measuring carpet, pumping gas, and weighing fish ... Myanmar, Liberia, an the USA ... the scientists do their work in the SI/MKS/metric system.

calculate the potential energy stored in a meta ball of mass of 80 kg kept at a height of 15m from the earth surface . What will be the potential energy when the metal ball is kept on the earth surface Take (g- 9.8 m/s] ​

Answers

Answer:

11760 J

Explanation:

cuz potential engery is PE = MHG

SO 80×15×9.8= 11760 J

Answer:

11769j

Explanation:

here,

mass(m)=80 kg

height(h)=15m

acceleration due to gravity(g)=9.8m/s^2

now,

potential energy = m×g×h

= 80×9.8×15

= 11760j

please help me with this I really need help​

Answers

Answer:

Ask with your Science teacher

Explanation:

i do not know the ans

A ferrari has a mass of 1485kg.what is it's weight on Earth ​

Answers

F = m · g

m = 1485 kg

g = 10 N/kg

F = 1485 kg · 10 N/kg = 14 850 N = 14,85 kN

Answer: The weight on Earth is 14,85 kN.

6.
For a given prism the angle of incidence is changed from 0° and 90', the angle of deviation [ ]
b) decreases
c) first decreases and then increases
d) first increases and then decreases
a) increases

Answers

Answer:

increase

Explanation:

please mark as brainlyest

Answer

A.Increses

Explanation:

how do u calculate the kinetic energy of a ball of mass 0.25kg being kicked vertically upwards with a speed of 5m/s​

Answers

Answer:

3.125J

Explanation:

K.E.= 1/2(mass)(velocity)^2

K.E.=1/2(0.25)(5)^2=3.125

please help urgent have you ever seen the old “Pull the tablecloth out from under the dishes” trick? Use Newton’s 1st Law to explain the following:
a. In this trick, are the dishes “objects in motion,” or “objects at rest?”
b. If the dishes end up staying on the table, was an UNBALANCED FORCE applied to them? How do you know?

Answers

Answer:

I kinda dont remember the 1st law so search it up on

and it should tell u , but if u need any help from the

Please help have due very soon?thank you

Answers

The answer is :78 I think

In----- theory, the actual wishes that are threatening to the dreamers conscious awareness are disguised

Answers

Answer:

Unconscious wish fulfillment

Explanation:

Unconscious wish fulfillment

(In the unconscious wish fulfillment theory, the actual wishes of the dreamer that are threatening to the dreamer's conscious awareness are disguised.)

The sky is blue because: Select one: a. the index of refraction for air is slightly larger for blue than for red b. atomic hydrogen is blue c. air molecules tend to polarize light along a horizontal axis d. oxygen and nitrogen molecules are small compared to the wavelengths of visible light e. oxygen molecules have a lower energy ground state than nitrogen molecules

Answers

Answer:

a. the index of refraction for air is slightly larger for blue than for red

Hideki had normal vision for most of his life, but now that he is in his 60s, he has started to have difficulty focusing on near objects. He went to an optometrist, who explained that his vision problem was the result of the lenses in his eyes losing elasticity due to aging. Which condition does Hideki have

Answers

Answer:

He is suffering from hypermetropia.

Explanation:

There are some defects of vision.

Longsightedness of hypermetropia : It is the defect of vision in which the person is not able to see the nearby objects clearly but can see the far off objects clearly. This is due to the elongation of size of eye ball. It is cured by using convex lens of suitable focal length.

Nearsightedness or Myopia : It is the defect of vision in which a person is not able to see the far off objects clearly but can see the nearby objects clearly. It is due to the contraction in the size of eye ball. It is cured by using concave lens of suitable focal length.

So, Hideki is suffering from hypermetropia. So, he should use the convex lens of suitable focal length.  


A particular electric car is supplied with 300 kJ of chemical energy by the battery. Of this, a total of 70.5 kJ of energy is wasted as heat.
Calculate the overall efficiency of the electric car.

Answers

Supplied energy=300kJ

Wasted energy=70.5J

Used energy:-

[tex]\\ \sf\longmapsto 300-70.5=229.5kJ[/tex]

We know

[tex]\boxed{\sf Efficiency=\dfrac{Used\:Energy}{Supplied\:Energy}\times 100}[/tex]

[tex]\\ \sf\longmapsto Efficiency=\dfrac{229.5}{300}\times 100[/tex]

[tex]\\ \sf\longmapsto Efficiency=\dfrac{229.5}{3}[/tex]

[tex]\\ \sf\longmapsto Efficiency=76.5\%[/tex]

The overall efficiency of the electric car = 76.5 %

To find the efficiency the given values are:

Energy supplied = 300 kJ

Energy wasted = 70.5 kJ

Define efficiency and calculate the value of efficiency.

      In the system the output energy is compared to the input energy is known as efficiency. That can be written as percentage ratio of output energy to the input energy.

Formula of efficiency is,

             Efficiency = ( E out / E in ) × 100

Here, Energy supplied = 300 kJ

so, energy used = Energy supplied - Energy wasted

                           = 300 - 70.5

                           =  229.5 kJ

Thus, substituting E out = 300 kJ , E in = 229.5 kJ

            Efficiency = ( 229.5 / 300 ) ×100

                             = 229.5 / 3

                             = 76.5

Hence, The overall efficiency of the electric car is 76.5 %

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