Ali while driving to school computes the average speed for his trip to be 20km/hr on his return trip along the same route. There is less traffic and average speed is 30km/hr. What is the average speed for Ali's trip?

Answer:

Oort cloud

Explanation:

The large reservoir of comet nuclei far beyond Pluto, from which we believe new long-period comets come into the inner solar system, is called Oort cloud.

The comets hich have the large periods that means more than 200 years to orbit the Sun generaly comes from Oort cloud hich is also knon as the cometary cloud.

Answer:

C: the process by which stars create the heavier elements

Explanation:

Stellar nucleosynthesis is defined as the process of nuclear fusion by which heavier elements are formed within stars by from the combination of protons and neutrons gotten from the nuclei of lighter elements.

Looking at the options, the correct one is Option C

Answer: C- the outer core

Explanation: The outer core is a thick layer of molten rock that encircles the inner core.

Answer:

40

Explanation:

vi=0

a=2

vf=?

d=400

vf^2=vi^2+2ad

vf^2=0+2×2×400=1600

vf=√1600=40m/s

Answer:

The moment of inertia should be decreased.

Explanation:

The torque is given by

Torque = Moment of inertia x angular velocity

To keep the torque constant, the spin rate be increased when the moment of inertia decreases.  

The moment of inertia of the body are the efforts to put the object in rotation.  

Answer:

65000g

24.325 hrs

7500m

Answer:

I) 65000 g   II)24.325 hours  III)7500 m

Explanation:

I) 1 kg = 1000 g

65 kg = 65 * 1000 g = 65000 g

II) 1 hour = 3600 seconds

1 second = 1/3600 hours

87570 seconds = 87570 * 1/3600 hours =24.325 hours

III) 1 km = 1000 m

7.5 km = 7.5 * 1000 m = 7500 m

Answer:

Option (a) is correct.

Explanation:

The electric charge is the inherent property of matter which appears due to the deficiency of charge or the excess number of electrons.

There are two types of charges, positive and negative.

When an object has deficiency of charge it becomes positive charge and when it gains some electrons, it becomes negative charge.

When the charge is in motion, it is called electric current and when the charge is at rest, it is called static current.

A charge at rest contributes the electric field only while the charge is in motion contributes the electric and magnetic field both.

Answer:

Acceleration is 1.2 m/s^2.

Explanation:

initial velocity, u = 0

distance, d = 60 m

time, t = 10 s  

Let the acceleration is a.

use second equation of motion

[tex]s= u t +0.5 at^2\\\\60 = 0 + 0.5 \times a \times 10\times 10\\\\a = 1.2 m/s^2[/tex]

Now according to the Newton's second law

Force = mass x acceleration

Let the mass is m.

F = m x 1.2 = 1.2 m Newton  

Answer:

the final speed of the first ball is 0.5 m/s

Explanation:

Given;

mass of the first body, m₁ = 8000 kg

mass of the second body, m₂ = 16,000 kg

initial velocity of the first body, u₁ = 2.5 m/s

initial velocity of the second body, u₂ = 0

final velocity of the stationary mass, v₂ = 1 m/s

let the final velocity of the first body = v₁

Apply the principle of conservation of linear momentum;

m₁u₁  +  m₂u₂  = m₁v₁   +   m₂v₂

8000(2.5)  +   (16,000 x 0)   =   8000v₁   +  16,000 (1)

20,000  +  0 = 8000v₁  +  16,000

8000v₁ = 4000

v₁ = 4000/8000

v₁ = 0.5 m/s

Therefore, the final speed of the first ball is 0.5 m/s

26. D. crushing the sugar cube and dissolving it in water.

27. A. atom

28. B. molecule

29. B. plum pudding model of Joseph John Thomson

30. B. He used cathode ray tubes which showed that all atoms contain tiny negatively charged subatomic particles or electrons

31. D. protons and neutrons are relatively heavier than electrons.

[tex]\boxed{\large{\bold{\blue{ANSWER~:) }}}}[/tex]

[tex]\sf What \: is \: acceleration? \\ \\ \sf The \: rate \: of \: change \: of \: velocity \: of \: an \\ \sf object \: with \: respect \: to \: time \\ \sf is \: known \: as \: acceleration. [/tex]

Answer:

A         Em

     1          ½ K

     2         ½ k 4 = 2k

     3         ½ k 9 = 4.5 k

     4         ½ k 16 = 8k

Explanation:

The total mechanical energy of a simple harmonic movement is constant in time, let's look for the energy at one end of the movement, where the velocity of the body is zero.

        Em = U = ½ k x²

at the end x = A

        Em = ½ k A²

Let's build a table for the energy and as a function of the amplitudes of the movement

     A         Em

     1          ½ K

     2         ½ k 4 = 2k

     3         ½ k 9 = 4.5 k

     4         ½ k 16 = 8k

as a function of the lowest energy

      1            Eo = ½ k

      2           4Eo

      3           9 Eo

      4          16Eo

Answer:

2 Hz.

Explanation:

Frequency is simply defined as the number of appearances of a periodic event occurring per time. It is usually measured in cycles/second.

Now, in this question, we are told that there are 2 cycles for each second.

Thus, we can say that the frequency is 2 cycles/1 s = 2 Hz.

Answer:

The magnetic force acting on the proton is 1.68 x 10^-18 N.

Explanation:

magnetic field, B = 5 T

speed , v = 2.1 m/s

charge q = 1.6 x 10^-19 C

Angle, A = 90 degree

The magnetic force on the charge particle is given by

[tex]F = q v B sin A\\\\F = 1.6\times 10^{-19}\times 2.1\times 5\times sin 90\\\\F = 1.68\times 10^{-18} N[/tex]

Answer:

Endothermic reaction

Explanation:

(a) Endothermic reaction: These are reactions that absorb heat from the surrounding during a chemical reaction. The enthalpy change for endothermic reaction is always positive,  and the energy level of the product is higher than that of the reactant

(b) Exothermic reaction: These are reactions that release heat to the surrounding during chemical reaction. The enthalpy change for exothermic reaction is always positive, and the energy level of the product is lower than that of the reactant.

From the diagram in the question,

Since the energy level of the product is higher than that of the reactant then the reaction is an endothermic reaction and as such, ΔH is positive

Answer:

3,500,000 J​

Explanation:

WORK = POWER * TIME

WORK= 5400 * 640

=6456000 J = 3,500,000 J​

Answer:

D

Explanation:

edge2021

Answer:

C. 9.9 cm

Explanation:

The location of the object, u = 14 cm

The location of the image, v = 5.8 cm

The focal length of the mirror, f = Required

The mirror formula for a convex mirror is given as follows;

[tex]\dfrac{1}{u} -\dfrac{1}{v} = -\dfrac{1}{f}[/tex]

Therefore, we get;

[tex]\dfrac{1}{14 \ cm} -\dfrac{1}{5.8 \ cm} =- \dfrac{41}{406 \ cm} = -\dfrac{1}{f}[/tex]

Therefore;

[tex]f = \dfrac{406 \ cm}{41} \approx 9.9 \ cm[/tex]

The focal length of the mirror, f ≈ 9.9 cm

Answer:

parallax

Due to foreshortening, nearby objects show a larger parallax than farther objects when observed from different positions, so parallax can be used to determine distances. To measure large distances, such as the distance of a planet or a star from Earth, astronomers use the principle of parallax.

Answer:

1-The liquid pressure is same at all points lying on the same horizontal plane in a stationary liquid.

2-The liquid pressure at a point inside the liquid is same in all directions.

3-The liquid pressure at a point inside the liquid is directly proportional to the depth of that point from the free surface of liquid.

4-The pressure of liquid at same depth is different for different liquids. It is directly proportional to density of liquid. That is, for same depth the liquid pressure is larger for liquid of larger density.

Explanation:

Answer:

same value because both sides are equal

Explanation:

equal value

Explanation:

soln,

weight=600N

mass=?

gravity=9.8 m/s²

now,

hope it helps.

Answer:

m = 61.22 kg

Explanation:

F = 600 N

g = 9.8 m/s²

m = ?

F = mg

600 = m(9.8)

---> m = 61.22 kg

[tex] \green{\huge{\red{\boxed{\green{\mathfrak{QUESTION}}}}}} [/tex]

ELASTIC LIMIT, YIELD POINT AND ULTIMATE TENSILE STRENGTH.

[tex] \orange{\underline{\huge{\bold{\textit{\green{\bf{TOPIC}}}}}}} [/tex]

Mechanical Properties Of Solid.

[tex] \huge\green{\boxed{\huge\mathbb{\red A \pink{N}\purple{S} \blue{W} \orange{ER}}}}[/tex]

[tex] \bold{ \green{PART \: \: (1):-}} \\ \bold \green {{ ELASTIC \: \: LIMIT}}[/tex]

It is also called yield point

In this limit, energy provided to the material to cause deformation when removed then the material returns to its own shape and size.

In this limit each body shows elastic nature

[tex] \bold{ \red{PART \: \: (2):-}} \\ \bold \red {{YIELD \: \: STRENGTH}}[/tex]

It is the fix amount of the energy which causes fixed permanent set of deformation.

In this body shows plastic deformation.

The level of stress that corresponds to the yield point is referred to as the yield strength of the material.

[tex]\bold{ \purple{PART \: \: (3):- \:ULTIMATE }} \\ \bold \purple {{TENSILE \: \: STRENGTH}}[/tex]

It is the amount of the stress which causes permanent set of deformation after the yield point.

Body show perfect plastic deformation.

This shows a permanent set of deformation.

[tex] \red \star{Thanks \: And \: Brainlist} \blue\star \\ \green\star If \: U \: Liked \: My \: Answer \purple \star[/tex]

Answer:

C. Increase in back emf

Explanation:

As the current through the field winding decreases the field strength also decreases and the back-emf is reduced, as a result the motor speeds up.

When the motor begins to speed-up, an additional back EMF is generated due to induction which reduces armature current. This also results in reduced strength of the field flux. The back emf generated is not enough to reduce the armature current which could stop the acceleration of the motor and the motor further accelerates.

Answer:

English only

Explanation:

When solving problems related to Electric Fields, care must be taken about symmetries. In our particular case when we take a look to at the drawings of the attached file, we realize:

1.-By symmetry each dx associated at a, has an opposite dx with point b as reference. The respective dE ( the charge is uniform ) is the same, as the charge of the wire is positive the force and the Field on a test charge (+) located at h will be upward, therefore the components dEx will cancel each other and the Electric Field becomes E = Ey = ∫ 2×dE× cosθ

The solutions:

A) Ey = 4623 N/C

B) Ey = 19.34 N/C

E = Ey = ∫ 2×dE× cosθ

Here     cosθ   = h/ d   ⇒  cosθ = h/√h² + x²      dE = K× dQ / d²

d² = h² + x²

k = 8.9 ×10⁹ Nm²C⁻²  ;   dQ = λ×dx     λ = 150×10⁻⁹ C    h = 0.08 m

Then by substitution

Ey =  2 ∫[K× λ×dx/ (h² + x²) ] × h / √h² + x²

reordering that equation:

Ey = 2×K×λ×h ∫ dx / [√ ( h² + x² ) ]³          (2)

To solve the integral we make use of a change of variables

x = h × tanα     then   x² = h² ×tan²α   and  dx = h× sec²α dα

plugging that values in equation (2)

Ey  =  2×K×λ×h ∫  h× sec²α× dα / [√ ( h² + h²tan²α)]³

Ey  = 2×K×λ×h² ∫ sec²α× dα / [ h × √ (1 + tan²α)]³            1 + tan²α = sec²α

Ey = 2×K×λ×h²× ∫ (sec²α / h³× sec³α )×dα

Ey = 2×K×λ/h × ∫ ( 1 / secα dα

Ey = 2×K×λ/h × sinα             now we αneed to come back to our original variables:

as   x = h × tanα         tanα = x/h   then x is the opposite leg in a right triangle  and h the adjacent one then the hypothenuse is √ (h² + x²)         then    sin α = x/ √ (h² + x²)      

Ey = 2×K×λ/h × x/ √ (h² + x²) |₀⁰°⁰⁵

Ey  = 2×8.9×10⁹× 150×10⁻⁹× 5×10⁻²/8× 10⁻²× √ 10⁻² ( 8 + 5 )   N/C

Ey = 4623 N/C

To answer the second question again we will make use of symmetries if you look at drawing ( Figure 2 ) you see that again the components in direction of x-axis cancel each other and the components in y-axis direction will add. Then

Ey = ∫ dE× cosθ

following the same procedure  we will find:

Ey = ∫ [K×λ × dl/d²] × h/ d

The importan point here is that the radius of the circle is

2×π×r = 0.01      ( the length of the wire)  ⇒  r = 0.16×10⁻² m

And we need to take into account that the integration is over the circle and the length of the circle is 0.01 m or ××2×π×r. All other factors are constant. Then by substitution

Ey = [K×λ ×h×  / ( √ r² + h²)³ ] × 10⁻²    N/C

Ey = 8.9 × 10⁹ × 150× 10⁻⁹ × 6× 10⁻² × 10⁻² / √ 10⁻² ( 0.16 + 6)

Ey = 0.8 × 10² / 6

Ey = 19.34 N/C

Answer:

A. to reduce the loss of energy in the form of heat across the transformer

Explanation:

The core of the transformer is laminated to minimise the energy as they interfere with the efficient transfer of energy from the primary coil to the secondary one. The eddy currents cause energy to be lost from the transformer as they heat up the core - meaning that electrical energy is being wasted as heat.

Answer: prevent excitation light from reaching the detector

Explanation:

A fluorometer refers to the device that's used in the measurement of parameters that are of visible spectrum fluorescence. They also prevent excitation light from reaching the detector.

These parameters are used in the identification of the amount and presence of molecules in a medium.

Answer:

the brightest found are Blue - White with

Explanation:

The energy emission of objects increases with their temperature, specifically Wien described the process in an expression

          [tex]\lambda_{maximum}[/tex] T = 2,898 10⁻³

With this expression we can find the temperature of the stars by the color they emit.

Specifically the Sun has a color of 550 nm which corresponds to 5400K

bright stars have a BLUE color corresponding to 7500K

the brightest found are Blue - White with a temperature of 20000K

Answer:

The number of electrons flowing per second is [tex]4.375\times 10^{18}[/tex].

Explanation:

How many electrons per second pass through a section of wire that carries a current of 0.70 A.?

Current, I = 0.7 A

time, t = 1 s

According to the definition of current, let the charge is q.

q = I t

q = 0.7 x 1 = 0.7 C

Let the number of electrons is n.

[tex]n =\frac{q}{e}\\\\n = \frac{0.7}{1.6\times 10^{-19}}\\\\n = 4.375\times 10^{18}[/tex]

Answer:

D

Explanation:

The tectonic plates move on the mantle, sort of floating on it as they are part of the crust. When they collide things like mountain ranges form, and big earthquakes happen.