Which optical device can focus light to a point through reflection?

Answer:

An electrolytic cell converts electrical energy into chemical energy.

Explanation:

Answer:

the dependent variable is the material

Explanation:

because we change the material each time to test which is the best insulator.

this came up in my test today, so i can assure you it is correct!

Answer:

(a) Approximately [tex]105\; {\rm rad \cdot s^{-1}}[/tex].

(b) Approximately [tex]15.7\; {\rm m \cdot s^{-1}}[/tex], assuming that this cylinder is rotating along the axis that goes through the center.

Explanation:

The unit [tex]{\rm rpm}[/tex] stands for "revolutions per minute", where each revolution is [tex]2\, \pi[/tex] radians.

With an angular velocity of [tex]1000\; {\rm rpm}[/tex], this cylinder would turn [tex]1000\times 2\, \pi = 2000\, \pi[/tex] radians every minute ([tex]60\; {\rm s}[/tex]). Thus, the angular velocity of this cylinder would be:

[tex]\begin{aligned} \omega &= \frac{2000\, \pi\; {\rm rad}}{60\; {\rm s}} \\ &\approx 104.720\; {\rm rad \cdot s^{-1}}\end{aligned}[/tex].

A point at the rim of this cylinder would be at a distance of [tex]r = 15.0\; {\rm cm} = 0.150\; {\rm m}[/tex] from the axis of revolution of this cylinder. If the angular velocity of this cylinder is [tex]\omega[/tex], the tangential velocity of this point would be:

[tex]\begin{aligned} v&= \omega\, r \\ &= \frac{2000\, \pi}{60\; {\rm s}} \times 0.150\; {\rm m} \\ &\approx 15.7 \; {\rm m\cdot s^{-1}}\end{aligned}[/tex].

The initial velocity of the sled will be 7.34 m/sec. V is the initial velocity of the sled.

According to the law of conservation of momentum, the momentum of the body before the collision is always equal to the momentum of the body after the collision.

The given data in the problem is;

(m₁)  mass of child = 38 kg

(u₁) is the initial velocity child = 2.2 m/s

(m₂) is the mass of sled = 68 kg

(u₂) is the initial velocity of sled = ?

(v) is the velocity after collision = 5.5 m/s

According to the law of conservation of momentum;

Momentum before collision =Momentum after collision

[tex]\rm m_1u_1 + m_2u_2 = v(m_1 + m_2)\\\\(38 \times 2.2) + (68 \times V) = 5.5 \times (38+68) \\\\ 83.6 + 68V = 5.5 \times 106 \\\\ 83.6 + 68V =583 \\\\ \rm 68\ V= 583 -83.6 \\\\ \rm 68 \ V= 499.4\\\\ V= 7.34 \ m/sec[/tex]

Hence,the initial velocity of the sled will be 7.34 m/sec.

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Answer:

One would need to know how far apart the towns are:

T = SA / 40      time it takes for first cyclist to travel S1

T = SB / 60       time it takes for cyclist B to travel distance S2

SA + SB = S     the distance between the towns

SB = 60 / 40 SA = 1.5 SA

SA + 1.5 SA = S

S = 2.5 SA where cyclist travels distance SA

The time will depend on the separation of the towns.

The radius of the prop blade of an airplane is determined as 4.25 m.

The radius of the prop blade of an airplane is calculated as follows;

a = v²/r

where;

r = v²/a

r = (875²)/(180,000)

r = 4.25 m

Thus, the radius of the prop blade of an airplane is determined as 4.25 m.

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Hello!

We can use Ohm's Law to solve for the potential difference across a resistor given the current and resistance:

[tex]V = iR[/tex]

V = Potential Difference (? V)
i = Current (1.5 A)

R = Resistance (12 Ω)

Plug in the known values and solve.

[tex]V = (1.5)(12) = \boxed{18 V}[/tex]

361 cubic meters of habitable space was available in the skylab. None of the given options are correct.

NASA launched the first American space station, called Skylab.

The fuel tank of the Saturn SIV-B rocket stage served as the Skylab's residential quarters.

Skylab's livable capacity was large in comparison to the spacecraft that American astronauts had previously used 361 cubic meters.

Skylab offered 361 cubic meters of livable area.

Hence, none of the given options is correct.

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Answer:

Blood Type because DNA also contains blood type

The minimum initial speed of the dart so that the combination makes a complete circular loop after the collision is 58.5 m/s.

The minimum speed if given by tension in the wire;

T + mg = ma

T + mg = m(v²)/R

tension must be zero for the object not fall

0 + mg = mv²/R

v = √(Rg)

Use the principle of conservation of energy

K.Ef  = K.Ei + P.E

¹/₂mvf² = ¹/₂mv² + mg(2R)

¹/₂vf² = ¹/₂v² + g(2R)

¹/₂vf² = ¹/₂(Rg) + g(2R)

vf² = Rg + 4Rg

vf² = 5Rg

vf = √(5Rg)

vf = √(5 x 2.8 x 9.8)

vf = 11.7 m/s

Apply principle of conservation of linear momentum for inelastic collision;

5v = vf(20 + 5)

5v = 11.7(25)

5v = 292.5

v = 58.5 m/s

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By applying the law of universal gravitation, the distance between the milky way and the andromeda galaxy is equal to 4.2 × 10¹¹ meters.

Given the following data:

Scientific data:

Gravitational constant = 6.67 × 10⁻¹¹ m/kg²

In order to determine the distance between the milky way and the andromeda galaxy, we would apply the law of universal gravitation.

According to the law of universal gravitation, the distance between two astronomical bodies can be calculated by using this formula:

[tex]d = \sqrt{\frac{GmM}{F} }[/tex]

Substituting the parameters into the formula, we have;

[tex]d = \sqrt{\frac{6.67 \times 10^{-11} \times 2.0 \times 10^{30} \times 4.0 \times 10^{11}}{2.4 \times 10^{30}} }[/tex]

Distance, d = 4.2 × 10¹¹ meters.

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The proton's electrostatic force exerted on the electron will be 3.5×10¹² N.

It is a force imposed by one charge on another as a result of the field.

The electrostatic force produced by one line charge on another line charge separated by r is determined by the charge potency of each charge as well as the separation distance between them.

The electrostatic force is found as:

[tex]\rm F= \frac{Kq_1q_2}{R^2} \\\\ F= \frac{9 \times 10^ 9 \times 1.6 \times 10^{-19} \times -1.6 \times 10^{-19} }{(2.00\times 10^{-11})^2} \\\\\ F= 3.5 \times 10^{12} \ N[/tex]

Hence, the proton's electrostatic force exerted on the electron will be 3.5×10¹² N.

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The momentum of the object after the collision is  1500 kg. m/s.

When two bodies of different masses move together each other and have head on collision, they travel to same or different direction after collision.

The external force is not acting here, so the initial momentum is equal to the final momentum. In inelastic collision, after the collision, the two objects are stick together and final velocity is the common velocity for both the bodies.

Given is the chart show the masses and velocities of two colliding objects that stick together after a collision.

Object        Mass (kg)           Velocity (m/s)

A                   200                      15

B                     150                    - 10

Using the conservation of momentum principle, we have

m₁u₁ +m₂u₂ =(m₁ +m₂) v = Pf

Substitute the values, then the momentum after collision will be

200x15 +150x(-10) =Pf

Pf = 1500 kg. m/s

Thus, the  momentum after collision is 1500 kg. m/s.

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The formula (ma = F - Fg) is used to determine the net upward force acting on a body.

The net upward force acting on a body is the resultant or sum of all the upward forces acting on a body at a given time.

ma = F - Fg

where;

Thus, the formula (ma = F - Fg) is used to determine the net upward force acting on a body.

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Answer:

2nd and 4th statements.

Explanation

If voltage is constant ( k ) and I = V / R,

Then I is inversely proportional to R so if I increases R decreases and vice versa, according to that the second statement is correct not the first.

if current is constant, then v is directly proportional to R and vice versa..the 3rd statement is wrong

if resistance is constant v is directly proportional to I, then only the 4th is correct not the 5th

Answer:

option b

Step by step explanation:

a dull black surface is a good radiator of heat

Answer:

option b is the answer

In Freudian theory, substance abuse is one of the following an example of a Thanatos instinct, It includes aggression, trauma, and risky behaviors, Therefore the correct answer is option D

The psychoanalytic approach to adult personality development is built on the theories of Sigmund Freud. His beliefs addressed four topics: level of consciousness, personality structure, and stages of psychosexual development. These personality qualities interact to create anxiety, which needs to be controlled via a range of defense mechanisms. These strategies mask the true, anxiety-related causes of one's conduct.

Freud's theories also have limited applicability to the fields of gerontology and geriatric medicine because they postulate that personality development related to his stages of psychosexual development essentially ends in adolescence.

Thus, Substance abuse is one of the Thanatos instincts, which also include aggression, trauma, and risky behavior, according to Freudian theory. Option D is the correct answer.

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Answer:

2.53m/s

Explanation:

Initial momentum in a system= Final momentum in a system

65kg*3m/s+12kg*0m/s=(65kg+12kg)*v

195kgm/s=77kg*v

v=2.53m/s

If the kinetic energy of the train decreases from 314 J to 250 J, the gravitational potential energy of the system It increases from 2 J to 66 J.

The principle of conservation of mechanical energy states that the total mechanical energy of a system is always constant. This means that the sum of the potential and the kinetic energy does not change.

Thus, if the kinetic energy of the train decreases from 314 J to 250 J, the gravitational potential energy of the system It increases from 2 J to 66 J.

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Answer:

pure substance

Explanation:

yw

To answer this question, two equations are needed.

F = m * a (force = mass * accelaration)

Vf =Vi + (a * t) (final velocity = initial velocity + (accelaration * time)

Knowing that the force is 100 N and the mass is 50 kg we can use the first equation to solve for the acceleration which would be 2 m/s^2.

Plugging in all we know to the second equation we get:

150 m/s = 100 m/s + (2 m/s^2 * t)

This gives us t = 25 seconds

Answer:

Ball 3 (tennis ball)

Explanation:

Formula we are using :

acceleration = Force / mass

=============================================================

Ball 1 :

⇒ acceleration = 15 N / 0.5 kg

⇒ acceleration = 30 m/s²

===========================================================

Ball 2 :

⇒ acceleration = 15 N / 4.5 kg

⇒ acceleration = 30/9 m/s²

⇒ acceleration = 10/3 m/s²

⇒ acceleration = 3.33 m/s²

===========================================================

Ball 3 :

⇒ acceleration = 15 N/ 0.05 kg

⇒ acceleration = 300 m/s²

============================================================

On comparing, we see that Ball 3 (tennis ball) has the greatest acceleration.

Answer:

110 m/s

Explanation:

because if you subtract 450 from 340 you get 110

The frequency of an electromagnetic wave with wavelength of 10nm will be 3 × 10∧7 Hz and would belong to the X-ray or ultraviolet part of the electromagnetic spectrum due to its wavelength

What is frequency?

Frequency is defined as the number of oscillations of a wave per unit time and is measured in hertz(Hz).

It is also inversely proportional to the wavelength.

The frequency of an electromagnetic wave can be calculated using the formula;

frequency = velocity of light divided by the wavelength

f = v ÷ λ

Note that the velocity of light = 3 × 10 ∧8 m/s

Wavelength = 10nm

Frequency, f = 3 × 10∧8 ÷ 10 = 3 × 10∧7 Hz

Hence, the frequency of an electromagnetic wave with wavelength of 10nm will be 3 × 10∧7 Hz and would belong to the X-ray or ultraviolet part of the electromagnetic spectrum due to its wavelength.

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From rest, a rock is dropped from a garage roof. The roof is 6.0 meters above ground level. The rock will reach the earth at a speed of 10.849 meters per second.

The change of displacement with respect to time is defined as the velocity.  Velocity is a vector quantity.

it is a time-based component. Velocity at any angle is resolved to get its component of x and y-direction.

Given data:

V(Final velocity)=? (m/sec)

h(height)= 6.0 m

u(Initial velocity)=0 m/sec

g(gravitational acceleration)=9.81 m/s²

Newton's third equation of motion:

[tex]\rm v_y^2 = u_y^2+ 2gh \\\\\rm v_y^2 = 0+ 2gh\\\\\ v_y= \sqrt{2\times 9.81 \ (m/s^2)\times 6.0 (m)} \\\\ v_y=10.849 \ m/sec[/tex]

Hence, the velocity of the rock as it hits the ground will be 10.849 m/sec.

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Measured in joules - Thermal energy

Measured with a thermometer - Temperature

Does not depend on how much material there is - Thermal energy

Measured in degrees Celsius - Temperature

Increases if you heat something for longer - Thermal energy

Not sure what you mean by "breaks in the tension" but I suspect you mean the rope will come apart if the tension in the rope exceeds 1800 N.

In the free body diagram for the 500 N weight, we have a figure Y with the net force equations

• horizontal net force:

∑ F[hor] = T₁ cos(θ) - T₂ cos(θ) = 0

• vertical net force:

∑ F[ver] = T₁ sin(θ) + T₂ sin(θ) - 500 N = 0

From the first equation, it follows that T₁ = T₂, so I'll denote their magnitude by T alone. From the second equation, we have

2 T sin(θ) = 500 N

and if the maximum permissible tension is T = 1800 N, it follows that

sin(θ) = (500 N) / (3600 N)   ⇒   θ = arcsin(5/36) ≈ 7.9°

is the smallest angle the rope can make with the horizontal.