A brick is dropped from a high scaffold.
a. How far does the brick fall during this time?

Answer:

The third image

Explanation:

The one with the thumb pointing to the right

Answer:

3, correct on Edge 2020

Answer:

Sunbeams are seen because of light separated from water droplets and dust and smoke particles suspended in the air. If the cloud cover only has a few small holes in it, then separate rays of light will sprinkle light in every direction so you can see sunbeams.

Answer:

20cal/s

Explanation:

Question:

There are two questions. The first one has been answered:

From the formular, Power = Q/t = (kA∆T)/l

the amount heat depends on the duration of time interval, length of the iron rod, the thermal conductivity of iron and the temperature difference between the ends of the rod.

The amount of heat that flows through the rod by conduction during a given time interval does not depend upon the mass of the iron rod (D).

Second question:

The ends of a cylindrical steel rod are maintained at two different temperatures. The rod conducts heat from one end to the other at a rate of 10 cal/s. At what rate would a steel rod twice as long and twice the diameter conduct heat between the same two temperatures?

Solution:

Power = 10cal/s

Power = energy per unit time = Q/t

Where Q = energy

Power = (kA∆T)/l

k = thermal conductivity of iron

A = area

Area = πr^2

r = radius

Diameter = d = 2r

r = d/2

Area = (πd^2)/4

Length = l

∆T = change in temperature

10 = (kA∆T)/l

For a steel rod with length doubled and diameter doubled:

Let Length (L) = 2l

Diameter (D)= 2d

Area = π [(2d)^2]/4 = (π4d^2)/4

Area = 4(πd^2)/4

Using the formula Power = (kA∆T)/l, insert the new values for A and l

Power = [k × 4(πd^2)/4 × ∆T]/2l

Power = [4k((πd^2)/4) ∆T]/2l

Power = [(4/2)×k((πd^2)/4) ∆T]/l

Power = [2k(A) ×∆T]/l = 2(kA∆T)/l

Power of a steel that has its length doubled and diameter doubled = 2(kA∆T)/l

Recall initial Power = (kA∆T)/l = 10cal/s

And ∆T is the same

2[(kA∆T)/l] = 2 × 10

Power of a steel that has its length doubled and diameter doubled = 20cal/s

Answer:

A mutation causes a dog to be born with a tail that is shorter than normal. Which best describes this mutation? It is harmful because it obviously affects the dog’s survival. It is harmful because it affects the dog’s physical appearance. It is neutral because it does not obviously affect the dog’s survival. It is beneficial because it affects the dog’s physical appearance.

Explanation:

Answer:

C

Explanation:

:)))

Answer:

instruments

Explanation:

Answer:

Explanation:

According to first law of thermodynamics :

Q = ΔE + W

Q is heat added , ΔE is increase in the internal energy of the system and W is work done by the system .

Here Q = 36 KJ

ΔE = 14 kJ

Putting the values in the equation

36 = 14 + W

W = 36 - 14

= 22 kJ .

Work done by gas or system = 22 kJ.

Answer:

Explanation:

A fan pushes hot air out of a vent and into a room. The hot air displaces cold air in the room, causing the cold air to move closer to the floor.

The hot air displacing the cold air is an example of  transfer by

Answer:

-7.23 rad/s

Explanation:

Given that

Mass of the cockroach, m = 0.157 kg

Radius of the disk, r = 14.9 cm = 0.149 m

Rotational Inertia, I = 5.92*10^-3 kgm²

Speed of the cockroach, v = 2.92 m/s

Angular velocity of the rim, w = 3.89 rad/s

The initial angular momentum of rim is

Iw = 5.92*10^-3 * 3.89

Iw = 2.3*10^-2 kgm²/s

The initial angular momentum of cockroach about the axle of the disk is

L = -mvr

L = -0.157 * 2.92 * 0.149

L = -0.068 kgm²/s

This means that we can get the initial angular momentum of the system by summing both together

2.3*10^-2 + -0.068

L' = -0.045 kgm²/s

After the cockroach stops, the total inertia of the spinning disk is

I(f) = I + mr²

I(f) = 5.92*10^-3 + 0.157 * 0.149²

I(f) = 5.92*10^-3 + 3.49*10^-3

I(f) = 9.41*10^-3 kgm²

Final angular momentum of the disk is

L'' = I(f).w(f)

L''= 9.41*10^-3w(f)

Using the conservation of total angular momentum, we have

-0.068 = 9.41*10^-3w(f) + 0

w(f) = -0.068 / 9.41*10^-3

w(f) = -7.23 rad/s

Therefore, the speed of the lazy Susan after the cockroach stops is -7.23 and is directed in the opposite direction of the initial lazy Susan angular speed

b)

The mechanical energy of the cockroach is not converted as it stops

Answer:

1) What is the purpose of life

Explanation:

This is an age long question that arises out of human curiosity about the beginning, existence and subsequently what happens to life after its gone. There exist no natural laws or methods currently that addresses this question.

Answer:

The length of cable is 12.5 m

Explanation:

Since, the wrecking ball completes 1 oscillation, in the same time, as it takes for the rock to complete 5 oscillations.

Therefore,

Time Period of Wrecking Ball = 5 (Time Period of Rock)

Since,

Time Period of  Pendulum = 2π√(L/g)

Therefore,

2π√(L₁/g) = 5[2π√(L₂/g)]

√L₁ = 5√L₂

Squaring on both sides:

L₁ = 25 L₂

where,

L₁ = Length of Cable = ?

L₂ = Length of string = 0.5 m

Therefore,

L₁ = 25 (0.5 m)

L₁ = 12.5 m

Answer:

A) equal to the battery's terminal voltage.

Explanation:

When the capacitor is fully charged after long hours of charging , its  potential becomes equal to the emf of the battery and its polarity is opposite to that of battery . Hence net emf becomes equal . The capacitor itself becomes a battery which is connected in the circuit with opposite polarity . This results in the net emf and  current becoming zero . There is no charging current when the capacitor is fully charged .

Answer:

Check the explanation

Explanation:

Kindly check the attached image below to see the step by step explanation to the question above.

Answer:

The work will be "600 kJ/kg".

Explanation:

(1-a) ⇒ Constant Pressure

(a-2) ⇒ Constant Volume

The given values are:

In state 1,

Pressure, P₁ = 200 kPa

Volume, V₁ = 2m³

In state 2,

Pressure, P₂ = 1000 kPa

Volume, V₁ = 5m³

Now,

In process (1-a), work will be:

⇒ W₁₋ₐ = P₁(Vₐ - V₁)

On putting the values, we get

⇒ W₁₋ₐ = 200(5-2)

⇒         = 200(3)

⇒         = 600 kJ/kg

In process (a-2), work will be:

⇒ Wₐ₋₂ = 0

∴ (The change in the volume will be zero.)

So,

⇒ Total work = (W₁₋ₐ) + (Wₐ₋₂)

⇒                    = 600 + 0

⇒                    = 600 kJ/kg

Answer:

In electromagnetic waves, energy is transferred through vibrations of electric and magnetic fields. In sound waves, energy is transferred through vibration of air particles or particles of a solid through which the sound travels. In water waves, energy is transferred through the vibration of the water particles.

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mmnjnjlkdhfutydjfyiudtkcgvyftdcgvjyiluftgyiuyu  ( had to do that cuz it wouldn't let through)

Answer:

The temperature is [tex]T = -106 ^oC[/tex]

Explanation:

From the question we are told that

   The temperature is [tex]T_1 = T_t= T_a=15^oC[/tex]

   The  diameter is  [tex]d_1 = 0.5001 cm[/tex]

    The diameter of the hole [tex]d_2 = 0.500 \ cm[/tex]

    The coefficient of linear expansion for aluminum is [tex]\alpha _1 = 25 *10^{-6} \ ^oC^{-1}[/tex]

    The coefficient of linear expansion for  titanium is [tex]\alpha _2 = 8.5 *10^{-6} \ ^o C^{-1}[/tex]

According to the law of linear expansion

     [tex]d = d_o (1 + \alpha \Delta T )[/tex]

Where [tex]d_o[/tex] represents the original diameter

  So for aluminum

          [tex]d_a = d_1 (1 + \alpha_1 (T- T_a) )[/tex]

Where [tex]d_a[/tex] is the new diameter of aluminum

          [tex]T_a[/tex] is the new temperature of the aluminum

So for titanium

      [tex]d_t = d_2 (1 + \alpha_1 (T- T_t) )[/tex]

Where [tex]d_t[/tex] is the new diameter of  titanium

          [tex]T_t[/tex] is the new temperature of the aluminum

So for the aluminum rivets to fit into the holes

     [tex]d_a = d_t[/tex]

=>  [tex]d_1 (1 + \alpha_1 (T- T_a) ) = d_2 (1 + \alpha_2 (T- T_t) )[/tex]

       Making T the subject of the formula

     [tex]T = \frac{(d_1 - d_2 ) + (d_2 *\alpha_2 T_t) - d_1 \alpha_1 * T_a }{d_2 \alpha_2 - d_1 \alpha_1 }[/tex]

    Substituting values

     [tex]T = \frac{(0.501 - 0.500 ) + (0.500 *(8.5*10^{-6}) * 15) - 0.500* (25*10^{-6}) * 15 }{0.500 * (8.5 *10^{-6}) - 0.501 * (25 *10^{-6}) }[/tex]

    [tex]T = -106 ^oC[/tex]

Answer:

Explanation:

We shall use Ampere's circuital law to find magnetic field at required point.

The point is outside the circumference of two given wires so whole current will be accounted for .

Ampere's circuital law

B = ∫ Bdl = μ₀ I

line integral will be over circular path of radius r = 41 cm .

Total current  I  = 5A -3A = 2A .

∫ Bdl = μ₀ I

2π r B = μ₀ I

2π x .41  B = 4π x 10⁻⁷ x 2

B = 2 x 10⁻⁷ x 2 / .41

= 9.75 x 10⁻⁷ T . It will be along - ve Y - direction.

Answer:

a) [tex]\omega = 13.2t^2\frac{rad}{s^3}+2.80t\frac{rad}{s^2}[/tex]

b) [tex]\alpha=26.4t\frac{rad}{s^3}+2.80\frac{rad}{s^2}[/tex]

Explanation:

You have that the angular displacement is given by:

[tex]\theta=4.40t^3\frac{rad}{s^3}+1.40t^2\frac{rad}{s^2}[/tex]

a) the angular velocity is given by the derivative in time, of the angular displacement, that is:

[tex]\omega=\frac{d\theta}{dt}=\frac{d}{dt}[4.40 t^3 rad/s^3 + 1.40 t^2 rad/s^2]\\\\\omega=\frac{d\theta}{dt}=13.2t^2\frac{rad}{s^3}+2.80t\frac{rad}{s^2}[/tex]

b) the angular acceleration is the derivative, in time, of the angular velocity:

[tex]\alpha=\frac{d\omega}{dt}=\frac{d}{dt}[13.2t^2\frac{rad}{s^3}+2.80t\frac{rad}{s^2}]\\\\\alpha=26.4t\frac{rad}{s^3}+2.80\frac{rad}{s^2}[/tex]

Answer:

Time of flight=3.5 seconds

Speed at maximum height is 0

Explanation:

Φ=60°

initial velocity=u=20m/s

Acceleration due to gravity=g=9.8 m/s^2

Total time of flight=T

Final speed=v

question 1:

T=(2 x u x sinΦ)/g

T=(2 x 20 x sin60)/9.8

T=(2 x 20 x 0.8660)/9.8

T=34.64/9.8

T=3.5 seconds

Question 2

Speed at maximum height is 0

Answer:

K = U ( b )

Explanation:

The expression that describes the kinetic and potential energies at the point mid-way between to the highest and lowest points is  K = U

this is because at the midpoint between the highest point and the lowest point the height is expressed as( h/2) therefore potential energy at that point is expressed as m*g*h/2 therefore the remaining energy at this point will be considered the kinetic energy which will be = m*g*h/2 as well hence at midpoint Kinetic energy = potential energy

Answer:

Option A, Sea Breeze

Explanation:

Ssea breeze is a wind that blows from the ocean or any water body to the nearby land mass. This breeze is cold as compared to the air on land. The water in water bodies has high specific heat capacity and hence takes longer time to cool as compared to the surrounding objects. The warmer air over the land rises upward thereby reducing the pressure on land and hence the sea breeze starts flowing from region of high pressure (i.e above the water body) towards the low pressure region that is the land.

Hence, option A is correct

Answer:147 joules

Explanation:

Mass=m=5kg

Acceleration due to gravity=g=9.8m/s^2

Height=h=3 meter

Potential energy=m x g x h

Potential energy=5 x 9.8 x 3

Potential energy=147 joules

Answer:

All elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor. Arranged this way, groups of elements in the same column have similar chemical and physical properties, reflecting the periodic law.

Answer:

1. B

2. A

3. C

4. B

5. A

6. Muscular strength is different than muscular endurance because of the fact that muscular strength is the amount of force that can be exerted in one instance. Muscular endurance is how long that you can exert that force without being completely exhausted.

7. Some benefits to strength training is the increase in muscular endurance. There is also the benefit of better muscular strength.

Explanation:

Answer:

the answers the correct one is cη

Explanation:

In this simple pendulum experiment the student observes a significant change in time between each period. This occurs since an approximation used is that the sine of the angle is small, so

              sin θ = θ

with this approach the equation will be surveyed

     d² θ / dt² = - g / L sin θ

It is reduced to

      d² θ / dt² = - g / L θ

in which the time for each oscillation is constant, for this approximation the angle must be less than 10º so that the difference between the sine and the angles is less than 1%

The angle is related to the height of the pendulum

         sin θ = h / L

         h = L sin θ.

Therefore the student must be careful that the height is small.

When reviewing the answers the correct one is cη

Considering the approximation of simple harmonic motion, the correct option is:

(c) Make sure that the difference in height between the pendulum's release position and rest position is not too large.

According to Newton's second law in case of rotational motion, we have;

[tex]\tau = I \alpha[/tex]

Applying this, in the case of a simple pendulum, we get;

[tex]-mg\,sin\,\theta =mL^2 \,\frac{d^2 \theta}{dt^2}[/tex]

On, rearranging the above equation, we get;

[tex]mL^2 \,\frac{d^2 \theta}{dt^2} + mg\,sin\,\theta=0\\\\\implies \frac{d^2 \theta}{dt^2} +\frac{g}{L} sin \,\theta=0[/tex]

Now, if angular displacement is very small, i.e.; the bob of the pendulum is only raised slightly.

Then, [tex]sin\, \theta \approx \theta[/tex]

[tex]\implies \frac{d^2 \theta}{dt^2} +\frac{g}{L} \,\theta=0[/tex]

This is now in the form of the equation of a simple harmonic motion.

[tex]\frac{d^2 \theta}{dt^2} +\omega^2 \,\theta=0[/tex]

Comparing both these equations, we can say that;

[tex]\omega = \sqrt{\frac{g}{L}}[/tex]

[tex]T=2\pi\sqrt{\frac{L}{g}}[/tex]

This relation for the time period can only be obtained if the angular displacement is very less.

So, the correct option is;

Option (c): Make sure that the difference in height between the pendulum's release position and rest position is not too large.

Learn more about simple harmonic motion here:

https://brainly.com/question/26114128

Answer:

340 W

Explanation:

Power = change in energy / change in time

P = ΔKE / Δt

P = ½ mv² / Δt

P = ½ (90 kg) (15 m/s)² / (30 s)

P = 337.5 W

Rounded to 2 significant figures, the power is 340 W.

Answer:

b) 20 kJ

Explanation:

Efficiency of carnot engine = (T₁ - T₂ ) / T₁  Where T₁ is temperature of hot source  and T₂ is temperature of sink .

T₁ = 270 + 273 = 543K

T₂ = 50 + 273 = 323 K

Putting the given values of temperatures

efficiency = (543 - 323) / 543

= .405

heat input = 50 KJ

efficiency = output work / input heat energy

.405 = output work / 50

output work = 20.25 KJ.

= 20 KJ .

Answer:

Flying cars.

Explanation: