(a) Explain the advantage of using a plane mirror in optical testing.
explain your answer ​

The lens present in our eyes forms a real and inverted image on the retina. The optic nerves carry this image from the retina to the brain. The brain then processes this info to generate clear and virtual images. That's how we perceive objects as they are.

When the image is formed on our "Retina", the light sensitive cells of our Retina gets activated and they generate electric signals. These signals are send to brain by the optic nerves. The brain interprets the electric signals in such a way that we see an image in erect and of the same size as the object... MÅRK ÅS THE ẞRÅÏÑLÏËST.......

Answer:potential difference is more or less like voltage. Using ohms, V=IR

Where V is Voltage

I is Current =0.4A

R is Resistance=20ohms

V=0.4*20

V=8V

Hence the potential difference will be 8V.

ii) V=0.4*30

V=12V

Explanation:

The voltage of potential difference is directly proportional to the current and the resistance. So if one increase or decrease, it will have impact on the other.

From the calculations, when the resistance increase, the voltage will increase to appreciate the change.

Answer:

White Lake was contaminated with the Chemical Complany dispersing their waste in the lake. Eventually, they were forced to stop dumping it into the lake

Answer:

2mol/L

Explanation:

Given parameters:

Number of moles of calcium carbonate = 2mol

Volume of solution = 1L

Unknown:

Molarity  = ?

Solution:

The molarity of a solution is the number of moles of solute dissolved or contained in a solution:

 Molarity  = [tex]\frac{number of moles }{volume }[/tex]  

 Molarity  = [tex]\frac{2}{1}[/tex]   = 2mol/L

Answer:

[tex]50\:\mathrm{m\: North}\\50\sqrt{3}\:\mathrm{m\: East}[/tex]

Explanation:

We can create a 30-60-90 triangle. The distance she walked is then the hypotenuse of the triangle, and using 30-60-90 triangle rules, we have the following:

The North leg is opposite to the [tex]30^{\circ}[/tex] angle. Therefore, if we call this distance [tex]y_N[/tex], we have the following:

[tex]\sin 30^{\circ}=\frac{y_N}{100},\\\frac{1}{2}=\frac{y_N}{100},\\y_N=\fbox{$50\:\mathrm{m}$}[/tex].

The East leg is opposite to the [tex]60^{\circ}\\[/tex] angle. If we call this distance [tex]x_E[/tex], we have:

[tex]\sin 60^{\circ}=\frac{x_E}{100},\\\frac{\sqrt{3}}{2}=\frac{x_E}{100},\\x_E=\fbox{$50\sqrt{3}\:\mathrm{m}$}[/tex].

Answer:

11.025m

Explanation:

In this question there is no vertical velocity,

t= 1.5s

Height of platform=h

From Newton equation

s = ut + 1/2gt^2

But there is no vertical velocity,

Hence,

Then u=0

h = 0 + 1/2 x 9.8 x (1.5)^2

h = 11.025m

Answer: Jack.

Explanation:

Momentum is defined as the quantity of motion.

For an object that has a mass M, and a velocity V, the momentum is written as:

P = M*V

For this problem, we know that Jack and Jill had the same speed (so they had the same velocity), let's say that this velocity is v.

Then the momentum of Jack will be:

P = 90kg*v

And the momentum of Jill will be:

P = 50kg*v

We can see that Jack will have a larger momentum, and this is because he has a larger mass than Jill, but the same velocity as her.

Answer:

180.7km/hr²

Explanation:

Given parameters:

Initial velocity  = 10miles/hr

Final velocity  = 25miles/hr

Time taken = 5minutes

     To hr

               60min  = 1hr

               5min gives 0.083hr

Unknown:

Acceleration  = ?

Solution:

To solve this problem,

   Acceleration  = [tex]\frac{v - u}{t}[/tex]  

v is the final velocity

u is the initial velocity

  Acceleration  = [tex]\frac{25 - 10}{0.083}[/tex]   = 180.7km/hr²

Explanation:

A gas at higher temperature is able to gain more heat from the environment/surroundings and has more kinetic energy to diffuse at a faster rate.

Hence a temperature at -20°C is more ideal.

Molar mass of H2S = 34.07g/mol

Molar mass of HCl = 36.45g/mol

Since H2S has a smaller molar mass, the same number of moles of H2S gas will diffuse faster as compared to the same number of moles of HCl gas.

Hence the answer is Hydrogen sulfide at -20°C. (D)

Answer:

19.6N

Explanation:

Given parameters:

Mass of rock = 2kg

Speed  = 30m/s

Unknown:

Net force on the rock  = ?

Solution:

The net force acting on this rock is a function of the acceleration due to gravity acting upon it.

 Net force  = weight  = mass x acceleration due to gravity

 Net force  = 2 x 9.8  = 19.6N downward

Answer:

2s

Explanation:

Given parameters:

Distance  = 30m

Speed  = 15m/s

Unknown:

Time before Laurence caught it = ?

Solution:

To solve this problem;

    Speed  = [tex]\frac{disance }{time}[/tex]  

 Time taken  = [tex]\frac{distance }{speed }[/tex]   = [tex]\frac{30}{15}[/tex]  = 2s

The time it takes is 2s

Given:

We will solve:

Speed  = [tex]\frac{distance}{time}[/tex]

Time taken  = [tex]\frac{distance}{time}[/tex] = [tex]\frac{30m}{15m/s}[/tex] = 2s

The time it takes is 2s

Answer:

Displacement

Explanation:

Displacement is a term used to represent change in position.

Answer:

c

Explanation:

mark ma es brainliest

When two charged objects are moved to 2  meters apart from 1 meter. Then, both Gravity and electrostatic forces will be weak.

The electrostatic force and gravity force is inversely proportional to square of distance between two objects.

                      [tex]F\alpha\frac{1}{r^{2} }[/tex]

Where r is distance between both charged objects.

When two charged objects are moved to 2  meters apart from 1 meter. Then, both Gravity and electrostatic forces will be weak.

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Answer:

2.7

Explanation:

The following data were obtained from the question:

Mass (m) of box = 100 Kg

Length (L) of ramp = 4 m

Height (H) of ramp = 1.5 m

Mechanical advantage (MA) of ramp =?

Mechanical advantage of a ramp is simply defined as the ratio of the length of the ramp to the height of the ramp. Mathematically, it is given by:

Mechanical Advantage = Lenght / height

MA= L/H

With the above formula, we can obtain the mechanical advantage of the ramp as follow:

Length (L) of ramp = 4 m

Height (H) of ramp = 1.5 m

Mechanical advantage (MA) of ramp =?

MA = 4/1.5

MA = 2.7

Therefore, the mechanical advantage of the ramp is 2.7

Answer:

holla at me!!!!!!!!!!????

Answer:

C, T=D/S

Explanation:

Answer:

The higher the skater is the more potential energy he has. As his height decreases, his potential energy decreases and his kinetic energy increases.

Explanation:

Make me BRAINLIST please

Answer:

The higher the skater is the more potential energy he has. As his height decreases, his potential energy decreases, and his kinetic energy increases. ... Explore how the skater's change in speed relates to the potential and kinetic energy of the skater.

Explanation:

(Via Uteach)

Answer: parasitic organisms cause harm to other organisms.

Answer:

parasitic organisms cause harm to other organisms.

Explanation:

Recall that

v ² - v₀² = 2 a ∆x

where

v₀ = initial velocity

v = final velocity

a = acceleration

∆x = distance

Then

(500 m/s)² - (90 m/s)² = 2 (1.5 m/s²) ∆x

∆x = ((500 m/s)² - (90 m/s)²) / (2 (1.5 m/s²))

∆x ≈ 80,633 m

Answer:

???

Explanation:

Answer:

22.4

Explanation:

That is the velocity

The age of the sample can be determined using the first order equation of the nuclear decay. The age of the parent isotope here is 45 years.

Unstable radioactive nuclei undergo nuclear decay to produce more stable nuclei with more life time. The time required to decay half of the initial amount of a material is called its half life.

The half life of a sample is related with the decay constant k as follows:

k = 0.693/t1/2

Given that, t1/2 = 15 years

k = 0.693/15 = 0.0462 yr⁻¹

The first order equation of the decay process is written as:

k = 1/t ln w0/wt

where w0 is the initial amount and wt be the amount after time t.

then t = 1/k ln w0/wt

Given that, the sample was decayed to one eighth of the initial amount .

t = 1/k ln 8

 = 1/0.0462 ln 8

 = 45 years.

Therefore, option C is correct.

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Answer:

Diagram 1

Explanation:

In diagram one, the earth is leaning toward the sun, meaning it is summertime.

The person will experience summer in diagram one because the earth is tilted towards the sun.

From diagram one we can see that earth is tilted towards the sun. During summer, the North Pole of the earth is tilted towards the sun.

As a consequence, the sun’s path is higher in the sky, causing the northern hemisphere to receive more light and heat.

In addition, because the sun is in the sky for more hours, the summer solstice is also the longest day of the year.

These extra hours of sunlight give the sun more time to heat the earth and this is the main reason for summer to be the hottest season.

During summer the sun is perpendicular to the tropic of cancer and heats more areas that lie in the tropic of cancer.

Thus the answer will be diagram 1 because the earth is tilted towards the sun.

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Answer:

1500 north

Explanation:

Answer: 1500 north

Explanation:

Impulse is change of momentum. Since the numbers are already in units of momentum, you just need to subtract one from the other to find the impulse. 4000 - 2500 = 1500. Because the bobsled is traveling south and slowing down, the impulse will be in the opposite direction, or north.

1500 north.

Answer:

F=m*g is the formula and the answer is 19,620 kg

Explanation:

Since the formula is F=m*g and Earth's gravity is 9.81 m/s^2 all you need to do is multiply 2,000 by 9.81

Answer:

[tex]20,000\:\mathrm{N}[/tex]

Explanation:

The weight of an object on Earth is equal to the force of gravity on that object.

We can use the following equation to determine the force of gravity on an object:

[tex]F_g=ma_g=mg[/tex], where [tex]m[/tex] is the mass of the object and [tex]g[/tex] is acceleration due to gravity ([tex]9.81\: \mathrm{m/s}[/tex]).

Solving, we get:[tex]F_g=2,000\cdot9.81=19,620=\fbox{$20,000\:\mathrm{N}$}[/tex] (one significant figure).

Answer:D

Explanation:

Answer:

B. 560 J

J. 1.2 m

Explanation:

v = Final velocity = 0

u = Initial velocity = 4 m/s

[tex]\mu[/tex] = Coefficient of friction = 0.7

m = Mass of runner = 70 kg

g = Acceleration due to gravity = [tex]9.81\ \text{m/s}^2[/tex]

Kinetic energy is given by

[tex]K=\dfrac{1}{2}m(v^2-u^2)\\\Rightarrow K=\dfrac{1}{2}\times 70\times (0^2-4^2)\\\Rightarrow K=-560\ \text{J}[/tex]

The mechanical energy lost is 560 J

Acceleration is given by

[tex]a=-\mu g\\\Rightarrow a=-0.7\times 9.81\\\Rightarrow a=-6.867\ \text{m/s}^2[/tex]

From kinematic equations we get

[tex]v^2-u^2=2as\\\Rightarrow s=\dfrac{v^2-u^2}{2a}\\\Rightarrow s=\dfrac{0^2-4^2}{2\times -6.867}\\\Rightarrow s=1.165\approx 1.2\ \text{m}[/tex]

The runner slides for 1.2 m

a. The amount of mechanical energy that is lost because of friction acting on the runner is: B. 560 J

b. The distance the runner slide is equal to: J. 1.2 m

Given the following data:

Acceleration due to gravity, g = 9.8 [tex]m/s^2[/tex]

a. To determine the amount of mechanical energy that is lost because of friction acting on the runner, we would calculate the change in kinetic energy:

Mathematically, the change in kinetic energy is given by the formula:

[tex]\Delta K.E = \frac{1}{2} m(v-u)^2[/tex]

Substituting the parameters into the formula, we have;

[tex]\Delta K.E = \frac{1}{2} \times 70(4-0)^2\\\\\Delta K.E = 35(4)^2\\\\\Delta K.E = 35 \times 16\\\\\Delta K.E = 560\;Joules[/tex]

Mechanical energy = 560 Joules

b. To determine how far (distance) the runner slide:

First of all, we would find the runner's acceleration.

[tex]Acceleration = ug\\\\Acceleration = 0.70 \times 9.8[/tex]

Acceleration = 6.86 [tex]m/s^2[/tex]

For distance:

[tex]V^2 = U^2 + 2aS\\\\4^2 = 0^2 + 2(6.86)S\\\\16=13.72S\\\\S=\frac{16}{13.72}[/tex]

Distance, S = 1.2 meters.

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