Sometimes on a sunny day campers start a campfire using a small mirror to light paper or dry grass. What shape of mirror would you use for this purpose? Explain your choice using reasoning.

KE=1/2mv^2

1/2(100)6^2

1800 J

Answer:

False

Explanation:

First we need to know the definition of work.

Work is done when a body moves through a distance with an applied force.

When swimming in water, you exert a force while moving through a distance. Therefore, work is done!

Answer: V = 299,958589.8 m/s

Explanation: To calculate Rigel velocity relative to us, we should use doppler effect formula.

Fo = (c + Vo) f/ ( c - Vs)

Fo/f = (c + Vo) / ( c - Vs)

If Vo = Vs = V approximately

4.26 × 10^10 = (3×10^8 + V) 6.17×10^14/(3×10^8 - V)

4.26×10^10/6.17×10^14 = (3×10^8 + V)/(3×10^8 - V)

6.9×10^-5 = (3×10^8 + V)/(3×10^8 - V)

Cross multiply

20713.13 - 6.9×10^-5V = 3×10^8 + V

Collect the like terms

6.9×10^-5V + V = 3×10^8 - 20713.13

1.000069V = 299979286.9

V = 299979286.9/1.000069

V = 299,958589.8 m/s

Therefore, Rigel's velocity relative to us is 299,958589.8 m/s

Explanation:

It is given that,

Speed of an automobile is 25 km/h or 6.95 m/s

Kinetic energy of the automobile is [tex]10^4\ J[/tex]

(a) Kinetic energy of automobile s given by :

[tex]K=\dfrac{1}{2}mv^2\\\\m=\dfrac{2K}{v^2}\\\\m=\dfrac{2\times 10^4}{(6.95)^2}\\\\m=414\ kg[/tex]

(b) If the velocity of the car is increased to 45 km/hour or 12.5 m/s, new kinetic energy becomes :

[tex]K=\dfrac{1}{2}\times 414\times (12.5)^2\\\\K=32343.75\ J[/tex]

(c) If the velocity is increased to 80 km/hour, 22.23 m/s, So

[tex]K=\dfrac{1}{2}\times 414\times (22.23)^2\\\\K=102293.79\ J[/tex]

Hence, this is the required solution.

Answer:

i. increasing the number of turns of the wire by half, so that it equals 300.

OR

ii. increasing the value of the current by half of its initial value, so that it equals 9 amp.

Explanation:

An electromagnet consists of a coil of wire wound around a conductor which becomes induced with magnetism when current flows through the coil.

The magnetic strength of the electromagnet can be increased to 1.5 of its initial strength either by;

i. increasing the number of turns by half of its initial value

OR

ii. increasing the current by half of its initial value

The magnetic strength of an electromagnet = I × N

where; I is the amount of current and N the number of turns.

Given that: I = 6 A, N = 200, then;

magnetic strength = 6 ×200

                              = 1200 Ampere turns

i. Increasing the number of turns to 300 and I = 6 A, we have;

magnetic strength = 6 × 300

                              = 1800 Ampere turns

OR

ii. increasing the value of current by half of its initial value, so that N = 200 and I = 9 A;

magnetic strength = 9 ×200

                              = 1800 Ampere turns

Answer: B

Explanation:

The reactivity of alkaline metal ( example group one ) increases down the group because of the increase in atomic mass from the top to the bottom of the group. As the mass increases, the force between the nucleus and the valence electron gets weaker and the atom will easily give up the electron as a result of this which eventually increases its reactivity.

The reactivity of halogens decreases as atomic mass increases. Therefore, option B is the correct answer.

Answer:

A larger image is produced when  [tex]d_i[/tex] > [tex]d_o[/tex]

A smaller image is produced when [tex]d_i[/tex] < [tex]d_o[/tex]

An upright image  is produced when m is positive

An upright image  is produced when m is negative

Explanation:

The mirror equation is given as follows;

[tex]\dfrac{1}{f} = \dfrac{1}{d_i} + \dfrac{1}{d_o}[/tex]

[tex]m =-\dfrac{d_i}{d_o} = \dfrac{h_i}{h_o}[/tex]

For concave mirrors, f = focal length

[tex]d_i[/tex] = Image distance from the mirror (-ve [tex]d_i[/tex] = Image is behind the mirror +ve [tex]d_i[/tex] = Image is in front of the mirror)

[tex]d_o[/tex] = Object distance from the mirror (-ve [tex]d_o[/tex] = Object is behind the mirror +ve [tex]d_o[/tex] = Object is in front of the mirror)

m = Magnification (-ve m = Inverted image +ve m = upright image)

[tex]h_i[/tex] = Image height

[tex]h_o[/tex] = Object height

f = Focal length of the mirror

To produce a larger image [tex]d_i[/tex] > [tex]d_o[/tex]

To produce a smaller image [tex]d_i[/tex] < [tex]d_o[/tex]

To produce an upright image, m should be positive hence, [tex]d_i[/tex] will be negative or the image will appear behind the mirror

To produce an inverted image, m should be negative hence, [tex]d_i[/tex] will be positive or the image will form in front of the mirror.

Answer:

375 j

Explanation:

Work done = increase in kinetic energy

C is the correct answer for this question. 375 work must be done on a 10 kg bicycle.

1:   1/5*10 * (10+5)(10-5)

Work Done: 375J

Hope this helps.

Answer:

10,000 N

Explanation:

Force = mass · acceleration

F = m · a

Jake's car:

Accelerates at 10 m/s²

Weighs 1000 kg

F = 1000 · 10

F = 10000 N

Answer:

10,000 Newtons

Please mark my answer.

Cheers, Jake

Answer: 44.89 times

Explanation:

Given that the earth's average velocity is about 6.7 times faster than that of planetoid Makemake

Given that the formula involved is:

R2/R1 = (V1/V2)^2

Let V1 = earth velocity and R1 = earth orbital distance

While R2 = Makemake velocity and R2 = orbital distance.

Since the earth's average velocity is about 6.7 times faster than that of planetoid Makemake, then,

V1/V2 = 6.7

Substitute this in the formula above

R2/R1 = (6.7)^2

R2/R1 = 44.89

Cross multiply

R2 = 44.89R1

Therefore, Makemake's orbit is about 44.89 times larger than the earth's orbit.

Answer:

Work done = 100 Nm

Potential energy = 250J

Explanation:

A person carrying a heavy weight of load without moving does no work. But the load will surely experience potential energy.

Work will be done when he or she covers a little distance.

If the weight of the load = 25 N and the distance covered is 4 metres, the workdone will be the product of the weight and distance covered. That is,

WD = F × d

WD = 25 × 4 = 100Nm

Let assume that the height of the man is 10 m tall.

The load will be experiencing potential energy of mgh. That is,

P.E = mgh

Since weight W = mg

Substitute weight and height into the formula

P.E = 25 × 10 = 250J

Answer:

tangential speed ≈ 2.7 m/s

Explanation:

formula: Vt = 2r / t

r = 3.5 m

t = 8.2 s

Vt = 2(3.5) / 8.2

Vt = 2.68184 m/s

Vt ≈ 2.7 m/s

correct on edge

Answer:

The current decreases

Explanation:

A P E X

Assuming that voltage remains constant, as its diameter decreases, its current decreases. hence option D is correct.

Current is a flow of charges. it is denoted by i and expressed in ampere A. Mathematically it is expressed as i = q/t, where q is the amount of charge and t is time. Current is nothing but amount of charges flown in the unit time in the electric wire. Charge is expressed in coulomb C and time in second s. hence coulomb per second (C/s) is ampere A. Charge on electron is 1.60217663 × 10⁻¹⁹C which is called as elementary charge.

There are two types of the current, Convectional current and non-conventional current. Convectional current is the current flows from positive to negative. Non convectional current flows from negative to positive. Note that flow of electrons is from negative to positive. Hence direction of flow of conventional current is from positive to negative.

In this problem, voltage is constant and diameter of the wire is decreasing,

The relation between resistance and and resistivity is

R = ρ l/A

When diameter decreases, cross sectionals area decreases, it increases resistance of the wire. and due to increase in resistance, current decreases in order to keep the voltage constant(V=IR).

Hence option D is correct.

to know more about Current :

https://brainly.com/question/13076734

#SPJ3.

Answer:

it will most likely turn off?

Answer: d)

Both Assertion and Reason are false

Explanation:

The least distance of distinct vision for normal human beings is 25 cm. That is,

normal eye can not be able to see clearly the objects placed closer than 25 Centimetre.

Havong an Assertion that normal human eye can see clearly all the objects below and above 25 cm is false. And since the assertion is false, the reason behind it is invalid. Therefore, having a reason that the human eye has the capacity to suitable adjust the focal length of its lens to a certain extent is also false.

Answer:

The correct option is D

D) Gestalt

Explanation:

In the earlier 20th century, a group of German scientists named Max Wertheimer, Wolfgang Köhler and Kurt Koffka, noticed that people tend to organzie a cluster of information into a Gestalt.

Gestalt is a German word which means the way things are placed or put together as a whole. In the field of phychology, it can be defined as a pattern or configuration. In this context, it included the human mind and its behavior as a whole.

The Gestalt theory states that:

"The whole of anything is greater than its parts and that attributes of the whole can't be deduced by analyzing any of the parts on their own accord"

Answer:

no

Explanation:

the goalie can move side to side but cant go out of the goalie box.

pls mark me brainliest

Answer:

radios work when electrons are speeding up and dow the attena, patters structure and shape make music pleasing to hear. (more info below)

Explanation:

a radio works when electrons are speeding up and down the antenna, sending out electromagnetic waves. Radiation waves travel through the air at the speed of light. When the radio waves reach the antenna, the electrons vibrate within the antenna and reproduce the initial signal. to make music pleasing to hear it has to have patterns, structure, shape.

hope this helped!

Answer:

Option B. 15miles.

Explanation:

From the question given, in the 4th hour simply means between 3rd and 4th hour.

Now, let us determine the position of the object at the 3rd and 4th hour. This is illustrated below:

At the 3rd hour:

Position (P3) = 60miles

At the 4th hour:

Position (P4) = 75miles

Finally, we shall determine the change in the position of the object as follow:

Change in the position = P4 – P3

Change in the position = 75 – 60

Change in the position = 15 miles

Therefore, the change in the position of the object in the 4th hour is 15miles.

Answer:

its b

Explanation:

i got it right on my exam

Answer: 15 orbits

Explanation:

Given that the

Radius of Mars = 2.28 × 10^8 km

Radius of Saturn = 1.43 × 10^9 km

For a linear speed,

One revolution = 2πR

One revolution of Mars = 2 × π 2.28×10^8

And

One revolutionary of Saturn = 2 × π × 1.43 × 10^9

Since the relationship between angular speed and linear speed is

V = wr

Or

W = V/2πR

The number of orbits that Mars completes in the time it takes for Saturn to complete one orbit will be

(Vs/2π × 1.43 × 10^9) ÷ (Vm/2π × 2.28×10^8)

Where

Vm = linear speed of Mars = 24.1 km/s

Vs = linear speed of Saturn = 9.7km/s

(24.1/2π × 2.28×10^8) ÷ (9.7/2π × 1.43 × 10^9)

(24.1/2π × 2.28×10^8) × ( 2π × 1.43 × 10^9/9.7)

2π Will cancel each other

(24.1/2.28 × 10^8) × (1.43×10^9/9.7)

(24.1 × 1.43×10^9)/(2.28×10^8 × 9.7)

3.4463×10^10 / 2.2116×10^9

15.58 times

Therefore, Mars will complete 15 orbits in the time it takes for Saturn to complete one orbit.

Answer:

[tex]E_T=[-27739.6\hat{i}-55479\hat{j}]\frac{N}{C}[/tex]

Explanation:

You have four charges at the corners of a square of side a=5.2cm

In order to calculate the electric field at the center of the square, you sum the contribution of the electric field generated by each charge.

The total electric field is given by:

[tex]E_T=E_1+E_2+E_3+E_4\\\\[/tex]    (1)

each contribution to the total electric field has two components x and y. The signs of the components depends of the direction of the field, which is given by the sign of the charge that produced the electric field. Then, you have

[tex]E_1=k\frac{q_1}{r^2}cos\theta\hat{i}-k\frac{q_1}{r^2}sin\theta\hat{j}\\\\E_1=k\frac{q_1}{r^2}(cos\theta \hat{i}-sin\theta \hat{j})[/tex]   (2)

q1 = 11.8*10^-9 C

k: Coulomb's constant = 8.98*10^9 Nm^2/C^2

For a square you obtain that

[tex]r=\sqrt{2}a=\sqrt{2}(5.2cm)=7.35cm=7.35*10^{-2}m[/tex]

and the angle is 45°

Then, you have in the equation (2):

[tex]E_1=(8.98*10^9Nm^2/C^2)\frac{11.8*10^{-9}C}{(7.35*10^{-2}m)^2}(cos45\° \hat{i}-sin45\° \hat{j})=[13869.7\hat{i}-13869.7\hat{j}]\frac{N}{C}[/tex]

In the same way you obtain for the other contributions to the total electric field:

For E2:

[tex]E_2=k\frac{q_2}{r^2}(cos45\°\hat{i}+sin45\° \hat{j})\\\\E_2=[13869.7\hat{i}+13869.7\hat{j}]\frac{N}{C}[/tex]

For E3:

[tex]E_3=k\frac{q_3}{r^2}(-cos45\°\hat{i}+sin45\°\hat{j})\\\\E_3=(8.98*10^9Nm2/C^2)\frac{23.6*10^{-9}C}{(7.35*10^{-2}m)^2}(-cos45\°\hat{i}+sin45\°\hat{j})\\\\E_3=39229.58(-cos45\°\hat{i}+sin45\°\hat{j})\frac{N}{C}\\\\E_3=[-27739.5\hat{i}+-27739.5\hat{j}]\frac{N}{C}[/tex]

for E4:

[tex]E_4=k\frac{q_4}{r^2}(-cos45\°\hat{i}-sin45\°\hat{j})\\\\E_4=[-27739.5\hat{i}-27739.5\hat{j}]\frac{N}{C}[/tex]

Finally, you sum component by component the four contributions to the total electric field (equation (1)):

[tex]E_T=[-27739.6\hat{i}-55479\hat{j}]\frac{N}{C}[/tex]

There still are four chargers in the corners of a square with side a=5.2cm. To compute the electric field just at the center of the composition, add the contributions of each shield's electromagnetic current.

entire electric field

[tex]\to E_T=E_1+E_2+E_3+E_4\ \ \ \ \ \ \ (1)[/tex]

Every contribution to the total electric field is comprised of two components, x, and y. These components' signs were determined by the direction of the field, which is determined by the sign of the charge that produced the electric field. There's

[tex]\to E_1=k\frac{q_1}{r^2}\cos\theta\hat{i}-k\frac{q_1}{r^2}\sin\theta\hat{j}\\\\\to E_1=k\frac{q_1}{r^2}(\cos\theta \hat{i}-\sin\theta \hat{j}) \ \ \ \ (2)\\\\\to q_1 = 11.8\times 10^{-9}\ C\\\\[/tex]

Coulomb’s constant (K) [tex]= 8.98\times 10^9\ \frac{Nm^2}{C^2}[/tex]

square, you obtain that

[tex]\to r=\sqrt{2}\\\\\to a=\sqrt{2}(5.2\ cm)=7.35\ cm=7.35\times 10^{-2}\ m[/tex]

angle= [tex]45\°[/tex]  then, you have in the equation (2):

[tex]\to E_1=(8.98\times 10^9\ \frac{Nm^2}{C^2})\frac{11.8 \times 10^{-9}\ C}{(7.35 \times 10^{-2}m)^2}(\cos 45^{\circ} \hat{i}-\sin 45^{\circ} \hat{j})[/tex]

         [tex]=[13869.7\hat{i}-13869.7\hat{j}]\ \frac{N}{C}[/tex]

Similarly, for other components to the overall electric field, you get:

For E2:

[tex]\to E_2=k\frac{q_2}{r^2}(\cos45^{\circ}\hat{i}+\sin45^{\circ} \hat{j})\\\\ \to E_2=[13869.7\hat{i}+13869.7\hat{j}]\ \frac{N}{C}[/tex]

For E3:

[tex]\to E_3=k\frac{q_3}{r^2}(-\cos45^{\circ}\hat{i}+\sin45^{\circ} \hat{j})\\\\\to E_3=(8.98\times 10^9 \ \frac{Nm^2}{C^2}) \ \frac{23.6 \times 10^{-9}\ C}{(7.35\times 10^{-2}\ m)^2}(-\cos45^{\circ} \hat{i}+\sin45^{\circ} \hat{j})\\\\\to E_3=39229.58(-\cos45^{\circ} \hat{i}+\sin45^{\circ} \hat{j})\frac{N}{C}\\\\\to E_3=[-27739.5\hat{i}+-27739.5\hat{j}]\ \frac{N}{C}\\[/tex]

For E4:  

[tex]\to E_4=k\frac{q_4}{r^2}(-\cos45^{\circ}\hat{i}-\sin45^{\circ}\hat{j})\\\\ \to E_4=[-27739.5\hat{i}-27739.5\hat{j}]\ \frac{N}{C}[/tex]

Finally, we add up the four contributions to the total electric field (equation (1)):

[tex]E_T=[-27739.6\hat{i}-55479\hat{j}]\frac{N}{C}[/tex]

Learn more:

brainly.com/question/14696059

Answer:

There were many examples of this. One of the most well-known not reversible reaction is a precipitation reaction, in which an insoluble solid is formed from two aqueous solutions. An example is the reaction between silver nitrate and sodium chloride which forms a silver chloride precipitate.

Answer:

18 cm to the right

Explanation:

I don't really know i'm just guessing. hope it's right.

Answer:

The mechanical advantage of the wheel and axle is the ratio of the distances from the fulcrum to the applied loads, or what is the same thing the ratio of the diameter of the wheel and axle

Explanation:

i looked on Google

The wheel and axle simple machine is closely related to gears. Like all other simple machines the wheel and axle system changes the force by changing the distance over which the force must be applied; if the input force is reduced to the output force, then the force must be applied over five times the distance.

Answer: 3

Explanation:

Since the phenotype ratio is 3 : 1, where red Roses are dominant over white roses, the ratio of red will be 3 while the white will be 1

Finding the value of the two roses will be;

3 + 1 = 4

For red roses,

3/4 × 4 = 3

For white rose,

1/4 × 4 = 1

Therefore, 3 of the red roses are there.

Answer:

3

Explanation: