IS IT B!! if not pls helpp!

(a) a thin layer of vacuum is provided between the two walls of flask, to minimise the heat loss by conduction , because for conduction medium (molecules) is required , but now medium is absent .

.(b) the two walls are silvered to minimise the heat loss by radiation , because a shiny surface is a bad absorber and bad emitter of radiation i.e. good reflector of heat , so prevents the heat exchange between content of flask and surrounding .

(c) the lid of flask is provided with a tight cork stopper to minimise the heat loss by convection , so that convection currents cannot go out .

(d) a plastic (or metal) case is provided with a flask , to protect the flask from physical damage

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Answer:

E = 50850[kJ]

Explanation:

To boil the water we must use the latent heat of vaporization. Also we need to multiply this value by the mass of the water.

[tex]E=m*H_{v}[/tex]

Where:

E = energy produced by heat [J]

m = mass = 225 [kg]

Hv = 226000 [J/kg]

[tex]E = 225*226000\\E = 50850000 [J]\\E=50850[kJ][/tex]

Answer:

31

Explanation:

In meiosis each sex cell has half the half the number of chromosomes than the parent cell. 62/2=31

Answer:

2) 7

3) 5

Explanation:

Answer:

the are are7

D

Explanation:

Answer:

2.97 meters

9.85 m/s^2

Explanation:

Given that :

Period (T1) = 3.45 seconds

When length , l is shortened by 1m, period (T2) = 2.81 seconds

Using the relation :

T = 2π√l/g

g = acceleration due to gravity

T1 = 2π√L/g - - - - (1)

Period 2:

x = shortened length = 1m

T2 = 2π√L-x/g - - - (2)

Square both sides

T1² = (2π)² L/g - - - (3)

T2² = (2π)² L-x/g - - (4)

Divide 3 and 4

(T2/T1)² = (L-x) / L

(2.81/3.45)^2 = (L - 1) / L

0.6633984 = (L - 1) / L

0.6633984L = L - 1

0.6633984L - L = - 1

−0.336601L = - 1

L = 1 / 0.336601

L = 2.9708764

Length = 2.97 meters

Acceleration due to gravity :

g = L(2π/T1)^2

g = 2.97(2π / 3.45)^2

g = 2.97 * 3.3168172

g = 9.8509

g = 9.85 m/s^2

g

Answer: It’s fiber optics so B

Answer:

Your brain is able to do this by comparing tiny differences in the way that sounds affect each ear. ... Signals from the ear travel along the auditory nerve to the brainstem, where each individual cell responds to a specific time difference and direction.

Explanation:

It's because of your ears.

Answer:

[tex]15\:\mathrm{J}[/tex]

Explanation:

The potential energy of an object is given by [tex]PE=mgh[/tex].

Recall that the weight of an object is equal to the force of gravity on the object. From this, we can set up the following equation and solve for the mass of the object:

[tex]F=mg,\\5=mg,\\m=\frac{5}{9.81}\approx 0.51\:\mathrm{kg}[/tex]

Now we can plug in values to [tex]PE=mgh[/tex] and solve:

[tex]PE=0.51\cdot9.81\cdot3=\fbox{$15\:\mathrm{J}$}[/tex].

Answer:

The potential energy of the body is 15J.

Explanation:

The energy possessed to a body due to position is called Potential energy.

U=mgh

U=mgh

U=5×3=15J

Hence, the potential energy of the body is 15J.

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Answer:

distance is how far away something has travelled from another object, while displacement is how far something is from the other object. Displacement is a vector quantity, unlike distance.

Answer:

Normal Force, Applied force, Gravitational Force, Spring Force

Explanation:

Normal Force so that he does not fall into trampoline, spring because the trampoline spring down when the force goes down, then up putting force upwards, gravitation because of gravity, and applied because of jumping

Answer:

i told u my thing got deleted lol

Explanation:

Answer:

B. The Law of Conservation of Energy

Explanation:

In Science, energy can be defined as the ability of an object or body to do work. There are two (2) main types of energy and these are;

I. Kinetic energy: it can be defined as an energy possessed by an object or body due to its motion.

Mathematically, kinetic energy is given by the formula;

Where, K.E represents kinetic energy measured in Joules.

M represents mass measured in kilograms.

V represents velocity measured in metres per seconds square.

II. Potential energy: it can be defined as an energy possessed by an object or body due to its position.

Mathematically, potential energy is given by the formula;

Where, P.E represents potential energy measured in Joules.

m represents the mass of an object.

g represents acceleration due to gravity measured in meters per seconds square.

h represents the height measured in meters.

Additionally, the various forms of energy are solar energy, electrical energy, chemical energy, thermal energy, wind energy, nuclear energy etc.

Hence, energy is never created of destroyed, it only transforms from one form to another" is the definition of The Law of Conservation of Energy.

Answer:

The resistance provided by the electrical elements is;

D. 0.375 Ohms

Explanation:

The relationship between the voltage, V, current, I, and resistance, R of an electric circuit is given as follows;

V = I × R

The given parameters of the circuit are;

The voltage provided by the car battery, V = 12 V

The current drawn by the air conditioning and lights, I = 32 A

From, V = I × R, we have;

R = V/I

Therefore, by substituting the known values, we have;

R = 12 V/(32 A) = 0.375 Ohms

The resistance provided by the electrical elements, R = 0.375 Ohms

Answer:

b. at the top

Explanation:

At the top of the climb, the vertical velocity of Jeff's throw has a value of zero.

Vertical velocity in this instance is acting against the acceleration due to gravity.

Answer:

1. Size

2. Shape

3. Color

Explanation:

Sorry if this is no help

Answer:

Refractive index is a measure of how light propagates through a material. The higher the refractive index the slower the light travels, which causes a correspondingly increased change in the direction of the light within the material.

Explanation:

Answer:

1.8 m/s

Explanation:

Step one:

given data

m1= 2kg

u1= 5m/s

m2= 5kg

u2= 1m/s

v1= 3m/s

From

m1u1+m2u2= m1v1+m2v2

substitute

2*5+5*1 = 2*3+5*v2

10+5= 6+5v2

15-6= 5v2

9= 5v2

divide both side by 5

v2= 9/5

v2= 1.8 m/s

Answer:

The speed of a wave would be 18 with a wavelength of 2 m and a frequency of 9 Hz.

Answer:

Acceleration = 0.5 m/s²

Explanation:

Given the following data;

Initial velocity, u = 1m/s

Final velocity, v = 3m/s

Time, t = 4 seconds

To find acceleration;

In physics, acceleration can be defined as the rate of change of the velocity of an object with respect to time.

This simply means that, acceleration is given by the subtraction of initial velocity from the final velocity all over time.

Hence, if we subtract the initial velocity from the final velocity and divide that by the time, we can calculate an object’s acceleration.

Mathematically, acceleration is given by the equation;

[tex]Acceleration (a) = \frac{final \; velocity - initial \; velocity}{time}[/tex]

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

Substituting into the equation, we have;

Acceleration = (3 - 1)/4

Acceleration = 2/4

Acceleration = 0.5 m/s²

The [x] component will be +57.47 a[x]  and the [y] component will be -30.51 a[y].

Any vector can be resolved along the axes of the cartesian coordinate system. For a two dimensional vector (say [V]), it can be resolved along the

[x] and [y] axis, such that the components of the vector are the vector's themselves and are given by -

[x] component = VcosФ a[x]

[y] component = VsinФ a[y]

Given is a vector is drawn on an X - Y plane. It has a magnitude of 65.1 centimeters and a direction of 28.0 degrees below the positive x-axis.

From the data given, we can write -

Magnitude of vector = |V| = 65.1

Angle made with +x axis = [Ф] =28 degrees {below the axis}

Therefore, the [x] component will be -

[x] = 65.1 x cos(28) = 57.47 a[x]

and the [y] component will be -

[y] = 65.1 x sin(28) = 30.51 × -a[y] = -30.51 a[y]

Therefore, the [x] component will be +57.47 a[x]  and the [y] component will be -30.51 a[y].

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Answer:

The object has an approximate mass of 4.06 kilograms.

Explanation:

Force is equal to mass times acceleration, so all we need to do is divide the force provided by the acceleration provided.

[tex]m = \frac{62.2N}{15.3 \frac{m}{s^2}}\\\\m = \frac{62.3kg\frac{m}{s^2}}{15.3 \frac{m}{s^2}}\\\\m = \frac{62.2kg}{15.3}\\\\m = 4.06kg[/tex]

Answer:

[tex]F_T=60132.52N[/tex]

[tex]P=15814852.76W[/tex]

Explanation:

From the question we are told that

Velocity of aircraft  [tex]V=263m/s[/tex]

Engine air intake rate [tex]\triangle M_a=85.9kg/s[/tex]

Fuel burn rate  [tex]\triangle M_f =3.92kg/s[/tex]

Velocity of exhaust gas [tex]V_e =921m/s[/tex]

Generally the Mass change rate of Rocket is mathematically given by

 [tex]\triangle M = \triangle M_a+\triangle M_f[/tex]

 [tex]\triangle M= 85.9+3.92[/tex]

 [tex]\triangle M=89.82kg/s[/tex]

Generally the Trust of the rocket is given mathematically by

 [tex]F_T=(\triangle M *V_e)-(dM_a/dt)*(V)[/tex]

 [tex]F_T=(89.82 *921)-(85.9)*(263)[/tex]

 [tex]F_T=60132.52N[/tex]

Generally the Rocket's delivered power is mathematically given by

Delivered power P

 [tex]P=V*F_T[/tex]

 [tex]P=263*60132.52N[/tex]

 [tex]P=15814852.76W.[/tex]

Answer:

Negative feedback caused his pancreas to produce more insulin.

Explanation:

Positive feedback is a feedback that causes an increase of product as a result of change while negative feedback is a feedback that causes a decrease in product as a result.

Negative feedback mechanism can be shown in the body as the control of blood sugar. The blood sugar is the product to be controlled. When there is an increase in blood sugar, the nerves sense a change. This change leads to secretion of insulin by the pancreas until homeostasis and then the secretion stops.

Answer:

negative feedback cause his pancreas to stop secreting insulin.

Explanation:

Answer:

Explanation:

Kinetic Energy formula:

KE = [tex]\frac{1}{2}[/tex]mv²

m=mass

v=speed

Given:

m=0.25kg

v=2.5m/s

Plug the values in:

KE = 1/2(0.25kg)(2.5m/s)²

KE = 0.78125 J (Joules)

Answer:

D. Upward force on the shuttle

Explanation:

The hot gas from space shuttles released downward causes an upward force on the shuttle and propels it up the more.

Answer:

Your awnser is B. Increase

Explanation:

Answer:

divide

Explanation:

u should divide the velocity by time interval because a=vf-vi/t

Answer:

Farmers

Explanation:

At the time of founding our country most soldiers in the revolutionary war were farmers who were inexperienced.

Answer:

D. farm workers

Explanation:

It is because when they started founding the country, people needed food and everything was based on agriculture and economy, and the main economy wat cotton and tobacco.

Answer:

[tex]a=5.34\ m/s^2[/tex]

Explanation:

Given that,

Initial velocity of a sprinter, u = 0

He runs a distance of 24m in 3 seconds.

We need to find his acceleration. Let a be his acceleration. Using second equation of kinematics to find it.

[tex]s=ut+\dfrac{1}{2}at^2\\\\24=0+\dfrac{1}{2}a(3)^2\\\\a=\dfrac{24\times 2}{9}\\\\a=5.34\ m/s^2[/tex]

So, the acceleration of the sprinter is [tex]5.34\ m/s^2[/tex].

The acceleration of the sprinter from rest to his top speed is 5.33m/s²,

Given the data in the question

Since the sprinter starts from rest,

Acceleration; [tex]a = \ ?[/tex]

To determine the acceleration of the sprinter, we use the second equation of motion:

[tex]s = ut + \frac{1}{2}at^2[/tex]

Where s is distance covered, u is initial velocity, a is acceleration and t is time.

We substitute our given values into the equation

[tex]24m = [0 * 3s] + [\frac{1}{2} * a * (3s)^2]\\\\24m = \frac{1}{2} * a * 9s^2\\\\24m = a * 4.5s^2\\\\a = \frac{24m}{4.5s^2} \\\\a = 5.33m/s^2[/tex]

Therefore, the acceleration of the sprinter from rest to his top speed is 5.33m/s²

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