can someone pls help me in this q
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A heat engine cannot have a thermal efficiency of 100% For all reversible processes, the second-law efficiency is 100%. The second-law efficiency of a heat engine cannot be greater than its thermal efficiency. The second-law efficiency of a process is 100% if no entropy is generated during that process

Explanation:

a.displacement is vector quantity there fore

we combine the two direction

[tex] {c}^{2} = \sqrt{ {a}^{2} + {b}^{2} } [/tex]

[tex] {c}^{2 } = \sqrt{ {12}^{2} + {16}^{2} } [/tex]

[tex] {c}^{2} = \sqrt{400 } [/tex]

[tex]c = 20[/tex]

displacement is 20km to wards north

b:average speed

[tex]v = s \div t[/tex]

20/3=6.67

c: please type correctly

Silk,wool, DNA, cellulose and protein

Geometric optics allows you to find which the correct answer about which false statement is:

  B)  All rays of light refracted by the lens pass through the principal focus.

Geometric optics studies the formation of images using the light geometric properties of optical systems, the main expression for this is:

      [tex]\frac{1}{f} = \frac{1}{p} + \frac{1}{q}[/tex]  

Where f is the focal length, p and q the distance to the object and the image respectively.

There are some points of special interest:

Let's analyze the claims.

A) True. A parallel ray comes from infinity and the image is formed at the focal point.

B) False. The image point is given by the expression above and depends on the distance to the object.

C) True. This is the definition of focal length.

D) True. All distances are measured from the main axis.

In conclusion, using geometric optics we can find that the correct answer about which false statement  is:  

      B)  All rays of light refracted by the lens pass through the principal focus.

Learn more about geometric optics here: brainly.com/question/2548694

Answer:  The magnitude of the ball's momentum change is  

      Δp=m∣ν  

i

​

−ν  

f

​

∣=(0.70kg)∣(5.0m/s)−(−2.0m/s)∣=4.9kg⋅m/s.

Explanation:

Answer:

C. Mechanical Energy

Explanation:

The total amount of mechanical energy is merely the sum of the potential energy and the kinetic energy.

Answer:

the direction of motion of the pulse

Answer:

Explanation:

d

Answer:

Earth because of greater gravity

Answer:it equals 0

Explanation:hope this is a good answer

Angular velocity is the ratio of angular displacement to time. Then the number of turns by the shaft is zero.

The rate of change of angular displacement is called angular velocity. It is a vector quantity.

We know that the angular velocity formula

[tex]\rm Angular \ velocity = \dfrac{Angular \ displacement}{time}[/tex]

The motor shaft turns through between the time when the current is reversed and the instant when the angular velocity is zero.

Then the number of turns will be

[tex]\rm Number \ of\ turns = Angular \ velocty \times time \\\\Number \ of\ turns = 0 *time \\\\Number \ of\ turns = 0[/tex]

The number of turns by the shaft is zero.

More about the Angular velocity link is given below.

https://brainly.com/question/7359669

The answer is option A. 0.75 m/s^2

the formula needed to solve this is acceleration = force/mass

we know the following:

mass of the backpack = 20KG

the force is 15N

therefor- acceleration = 15/20

which can also be written as 3/4, leaving us with the final answer of .75 m/s^2

Answer:

0.75 m/s2

Explanation:

0.75 m/s2

Explanation:

gravitational potential energy at the top of the hill, which transforms into kinetic energy as he moves bottom of the hill

that's mean potential energy transfoms into kinetic energy

His potential energy is converted into kinetic energy when his speed increases as he goes downhill.

Mechanical energy is the combination of all the energy in motion represented by total kinetic energy and the total potential energy stored energy in the system which is represented by total potential energy.

Total mechanical energy is s the sum of all the kinetic as well as potential energy stored in the system.

ME = KE + PE

When Andrew skis down a hill then he had stored potential energy due to the height of the hill and his gravitational weight,

Due to the height of the slope and his weight, Andrew had potential energy stored when he skied down it.

As he descended the hill, his speed increased, transforming this potential energy into kinetic energy.

Learn more about mechanical energy from here,

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Explanation:

Shorter wavelength since UV light has more energy than visible light

365 nm - What is the peak energy wavelength of UV light?  It allows both infrared daylight and ultraviolet night-time communications by being transparent between 320 nm and 400 nm and also the longer infrared and just-barely-visible red wavelengths. Its maximum UV transmission is at 365 nm

39°C=1.28L

8°C=? Less

=8°C/39°C×1.28L

=8/39×1.28L

=10.24/39

=512/195

=2.6L

Answer:

D

Unbalanced or net forces acting on the car will cause it to move

The correct answer is option D. The net force on the car is zero​.

Since the car is not accelerating, the force of air resistance and the friction force must add to give the exact opposite of the applied force. The net force here would be zero, as well.

Newton's First Law is the law of inertia. An object with no net forces acting on it which is initially at rest will remain at rest. If it is moving, it will continue to move in a straight line with constant velocity.

Learn more about Newton's First Law here:  https://brainly.com/question/11472821

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Answer:

Electromagnetic waves are waves that have no medium to travel whereas mechanical waves need a medium for its transmission. Electromagnetic waves travel in a vacuum whereas mechanical waves do not. The mechanical waves need a medium like water, air, or anything for it to travel.

Explanation:

Newton's second law allows to find the acceleration of the two-body system, where a mass is hanging is:

Newton's second law states that the net force on a body is equal to the product of the mass and the acceleration.

         ∑ F = m a

Where the bold letters indicate vectors, F is the force, m the mass and the acceleration of the body.

A free body diagram is that diagram of the system where the forces are shown without the details of the bodies. In the attachment we have a free-body diagram of the system.

Let's write Newton's second law for each axis.

x- axis

        T = m₁ a

y-axis

body in the horizontal part

        N-W₁ = 0

       N = W₁

Body hanging.  

         W₂ - T = m₂ a

Wwhere the positive direction is down, let's write our system of equations.

                T = m₁ a  

         W₂-T = m₂ a

Let's Resolve.

          m₂ g = (m₁ + m₂) a

          a = [tex]\frac{m_2}{m_1+m_2} \ g[/tex]  

Let's calculate.

         a =[tex]\frac{63}{10+63} \ 9.8[/tex]  

         a = 8.46 m / s²

In conclusion using Newton's second law we can find the acceleration of the two-body system, where a mass is hanging is:

Learn more about Newton's second law here:  brainly.com/question/13959891

Please find attached photograph for your answer.

Hope it helps.

Do comment if you have any query.

Answer:

Explanation:

That’s dangerous who would do that.

Me

Answer:

PE=0

Explanation:

If the tank is on the ground, there is 0 height which means the equation of PE=mh will be PE=12543(0)=0, hope this helps!

Using the Hubble law v = H₀d where v = recessional speed = 70,000 km per second H₀ = hubble constant = 70 km/s/Mpc and d = distance of galaxy.

Making d subject of the formula, we have

d = v/H₀

Substituting the values of the variables into the equation, we have

d = v/H₀

d = 70000 km/s/70 km/s/Mpc

d = 1000 Mpc

So, the galaxy is 1000 Mpc away from us.

Learn more about hubble law here:

https://brainly.com/question/18484687

Answer:

this is an example of Newton's Second Law, acceleration happens when a force acts on a mass.

the force that makes the bicycle move is your foot pushing against the pedal

Answer:

40 to 80

Explanation:

A car's kinetic energy changes with the speed.  Cars going slower have less potential energy than cars going faster.

Answer:

Explanation:

The kinetic energy of an object can be found by using the formula

[tex]k = \frac{1}{2} m {v}^{2} \\ [/tex]

m is the mass in kg

v is the velocity in m/s

To find the velocity we make v the subject of the equation

That's

[tex]v = \sqrt{ \frac{2k}{m} } \\ [/tex]

From the question

k = 76 J

m = 2.3 kg

We have

[tex]v = \sqrt{ \frac{2 \times 76}{2.3} } = \sqrt{ \frac{152}{2.3} } \\ = 8.129388...[/tex]

We have the final answer as

Hope this helps you

Please find attached photographs for your answer.

Hope it helps.

Do comment if you have any query.

Answer:

(B) The number of protons - only the number of protons in the nucleus determines the element - mass and neutrons can vary for the same element

Answer:

A force is a push or pull that acts on an object.

:)

Answer:

force

Explanation:

It's unit is in Newton

P= 10m = 10 x 115 = 1150 N

work done while lifting a 115 kg sofa 1.5 m off the ground :

A= Ph = 1150 x 1.5 = 1725 J

P/s: I think the weight first is 115kg

ok done. Thank to me :>

Answer:

Majors are also called concentrations. An academic major or concentration is a college or university student's main field of specialization during his or her associates or undergraduate studies which would be in addition to, and may incorporate portions of, a core curriculum.