An electric heater is 90% efficient. How much useful energy is produced from 8000 J?

Answer:

D. violet

Explanation:

think of a UV light

Answer:

Zero gravity

Explanation:

Astronauts around the earth either in spaceship, a space station or on a space walk appear to be weightless because of the zero gravity in such environment.

Weight is a function of the mass and acceleration due to gravity a body has.

   Weight  = mass  x  acceleration due to gravity

In a place where acceleration due to gravity is 0, the weight would be zero and a person would appear to be weightless.

Answer:

300

Explanation:

If the %DV is based on an average 2,000 calorie diet, and one gram of carbohydrate provides 4 calories, you would divide 2,000 by 4.

2,000 divided by 4 equals 500.

If Anna's doctor recommends 60% of her calories, you find out how much 60% of 500 is.

60% of 500 is 300.

Anna should consume 300 grams of carbohydrates daily.

Hope this helps!

Answer:

300

Explanation:

Answer:

The magnitude of the recoil velocity of the machine is 0.05  m/s.

Explanation:

Given;

mass of the baseball, m₁ = 0.101 kg

mass of the machine, m₂ = 67.1 kg

velocity of the baseball, v₁ = 32.6 m/s

let v₂ be the recoil velocity of the machine.

Apply the principle of conservation of linear momentum; the total momentum before and after firing the ball must be constant.

sum of the initial momentum of the ball and the machine = 0  (at rest)

sum of the final momentum of the ball and the machine = m₁v₁ + m₂v₂

Since total momentum is constant; m₁v₁ + m₂v₂ = 0

m₁v₁ + m₂v₂ = 0

(0.101 x 32.6) + (67.1)v₂ = 0

67.1v₂ = -3.2926

v₂ = (-3.2926) / 67.1

v₂ = -0.05  m/s (the negative sign shows that it is the opposite direction)

Thus, the magnitude of the recoil velocity of the machine is 0.05  m/s.

Answer:

The mass remains the same

Explanation:

An ice cube of mass 5g left in the sun in a beaker will have no mass difference.

For this system, mass is conserved.

Answer:

Explanation:

When a physical change occurs, the mass of the substance is conserved. This means that the total mass of the substance remains the same from beginning to end. The physical properties of the substance, such as size and shape, may change, but the amount of matter in the substance does not change.

( sample response )

Answer:

The positively charged particle will move towards the negatively charged particle.

Explanation:

According to Coulomb's Law, there are two types of charges--positive charge and negative charge. Coulomb said that they are either attractive or repulsive but the basic law in charges states that opposite attracts. Since they (the two charged objects) are oppositely charged, they will then move towards one another.

Answer:

d = 114.95 m

Explanation:

Givens:

a = 7.6 m/s^2

t = 5.5 s

v_i = 0 m/s

a = (v_f-v_i)/t

7.6 m/s^2 = (v_f-0 m/s)/5.5 s

v_f = (7.6 m/s^2)*(5.5 s)

v_f = 41.8 m/s

d = [(v_f+v_i)/2]*t

d = [(41.8 m/s)/2]*5.5 s

d = 114.95 m

Answer:

The energy stored in the bungee cord is 43,750 J.

Explanation:

Given;

extension of the bungee cord, x = 25 m

spring constant of the bungee cord, k = 140 N/m

The elastic potential energy stored in the bungee cord is calculated as;

U = ¹/₂kx²

U = ¹/₂(140)(25)²

U = 43,750 J

Therefore, the energy stored in the bungee cord is 43,750 J.

Answer:

Here's what I think,

A_Trigonometric_ratio (whatever)

The general form of sin/cos/tan(angle).

So here as in the general form the "whatever" is always an "angle" input which (may sound a bit unfair but) is a dimensionless quantity.

As mentioned in your question,

F= Asin(Bt) + C cos (Dy)

Dimentions of these terms will be same (by homogenity of dimensions).

So what we gotta do here is make Bt and Dy dimensionless for this whole equation to work.

According to your question t is time,

So to make Bt dimensionless,

B must be equal to inverse of time i.e T^(-1)

Using the same process on Dy, gives inverse of length i.e L^(-1)

So,

B= M^(0)L^(0)T^(-1)

D = M^(0)L^(-1)T^(0)

The dimension of D/B then will be M^(0)L^(-1)T^(1)

Answer:

The internal resistance of the cell is 0.051 ohm.

Explanation:

Given;

emf of the battery, E = 12 V

terminal voltage of the cell, V = 8.2 V

current in the circuit, I = 75 A

let the potential drop of the cell due to internal resistance (r) = Ir

The internal resistance of the cell is calculated from the equation below;

E = V + Ir

where;

r is the internal resistance of the cell

[tex]Ir = E - V\\\\r = \frac{E-V}{I} \\\\r = \frac{12-8.2}{75} \\\\r = 0.051 \ ohm[/tex]

Therefore, the internal resistance of the cell is 0.051 ohm.

Answer:

it is electron that is free to move in conductor

Answer:

229.5 km/h

Explanation:

Given that

Velocity of the plane relative to the ground = V.pg = ?

Velocity of air relative to the ground = V.ag = 90 km/h

Velocity of the plane relative to air = V.pa = 300 km/h

V.pg = V.ag + V.pa

Where

V.ag = 90 km/h

= -90 cos 45i - 90 sin 45j

V.pa = 300 km/h

= 300 cos θi + 300 sin θj

V.pg = [-90 cos 45i - 90 sin 45j] + [300 cos θi + 300 sin θj], on rearranging and collecting like terms

V.pg = [300 cos θ - 90 cos 45]i + [300 sin θ - 90 sin 45]j

If vector i = 0, then

300 cos θ - 90 cos 45 = 0

300 cos θ = 90 cos 45

cos θ = 90 cos 45 / 300

cos θ = 63.6396 / 300

cos θ = 0.2121

θ = cos^-1 0.2121

θ = 77.75

We then use this θ to find vector j

V.pg = 300 sin θ - 90 sin 45

V.pg = 300 sin77.75 - 90 sin45

V.pg = 293.1693 - 63.6396

V.pg = 229.5297 km/h

Answer:

Explanation:

Input​ refers to the amount of energy put into a device, and ​ output​ refers to the amount of energy that comes out. A device may change the type of energy but not the amount. For example, a light bulb's input energy is the form of electrical energy, and its output energy is in the form of light and heat. Efficiency.

Answer:

194.81 revolutions

Explanation:

Given that,

Initial angular velocity, [tex]\omega_i=3700\ rpm[/tex]

Final angular velocity, [tex]\omega_f=1800\ rpm[/tex]

Time, t = 4.25 seconds

We need to find the number of revolutions occur during this time.

3700 rpm = 387.46 rad/s

1800 rpm = 188.49 rad/s

Let [tex]\alpha[/tex] is angular acceleration. Using first equation to find it.

[tex]\alpha =\dfrac{\omega_f-\omega_i}{t}\\\\\alpha =\dfrac{188.49 -387.463 }{4.25}\\\\\alpha =-46.81\ rad/s^2[/tex]

Now let us suppose that the number of revolutions are [tex]\theta[/tex].

[tex]\theta=\dfrac{\omega_f^2+\omega_i^2}{2\alpha}\\\\=\dfrac{188.49 ^2-387.463 ^2}{2\times -46.81}\\\\=1224.087\ rad[/tex]

or

[tex]\theta=\dfrac{1224.087}{2\pi}\\\\=194.81\ rev[/tex]

Hence, there are 194.81 revolutions.

Answer:

the reading of the balance must decrease

Explanation:

The balance of the span is within a fluid the air, for which it is subjected to the pressure of the same, if we write the equilibrium equation we have

          F_net = B -W - F_armosphere

in this case F_net = 540 N

where the thrust is given by Archimedes' principle which states that the thrust is equal to the weight of the fluid dislodged

          B = ρ g V

in this case the density of the air is

           ρ = 1.1 kg / m³

therefore the value of the thrust is small

the force of the air is

            P = F / A

            F = P A

the air pressure is approximately P = 1 10⁵ Pa

Thus

      B <F_atmosphere

Now we can analyze what happens when we remove the air from the room, the pressure at atmospheric pressure decreases therefore the force of the air decreases, while there is some air the thrust is maintained even when it also decreases since the density of the air decreases when decreasing the Pressure.

Consequently, the reading of the balance changes depending on how the thrust and the air force decreases, in general the air force decreases much faster than the thrust, therefore the reading of the balance must decrease

Answer:

The height of the ball when the speed of the ball is half of its initial value is 16.5 m

Explanation:

Given;

maximum height reached by the ball, h = 22 m

let the initial velocity of the = u

The equation of maximum height reached by the ball is calculated as;

v = u² - 2gh

where;

v is the final velocity at the maximum height = 0

0 = u² - (2 x 9.8)22

0 = u² - 431.2

u² = 431.2

u = √431.2

u = 20.765 m/s

Half of the initial speed = ¹/₂ x 20.765 m/s = 10.383 m/s

The height of the ball at this half value of speed is calculated as;

v² = u² - 2gh

where;

v is the final speed = 10.383 m/s

u is the initial speed = 20.765 m/s

(10.383)² = (20.765)² - (2 x 9.8)h

(2 x 9.8)h = (20.765)² - (10.383)²

19.6h = 323.379

h = 323.379 / 19.6

h = 16.5 m

Therefore, the height of the ball when the speed of the ball is half of its initial value is 16.5 m

Answer:

13.94 to 2 d.p

Explanation:

just add them all up and i am confused the ones you said or the ones listed ?

the one i did was the listed ones

um I do not know sorry

Explanation:

ummmmmmjjhfgfffff

Answer:

O²⁻

Explanation:

Number of protons  = 8

Number of neutrons  = 9

Number of electrons  = 10

What type of atom or ion is it = ?

Solution:

Protons are the positively charged particle in an atom

Neutrons do not carry any charges

Electrons are negatively charged particles

 For this atom, the number of protons helps to identify what specie it is; so this is an oxygen atom.

Now,

     Charge  = Number of protons  - Number of electrons

      Charge  =  8  - 10  = -2

The charge on the atom is -2 and so it is an oxygen ion with -2 charge

 The ion is O²⁻

Answer:

8.13secs

Explanation:

From the question weal are given

Height H =324m

Required

time it takes to drop t

Using the equation of motion

H = ut + 1/2gt²

Substitute the given values

324 = 0(t)+1/2(9.8)t²

324 = 1/2(9.8)t²

324 = 4.9t²

t² =324/4.9

t² = 66.12

t = √66.12

t = 8.13secs

Hence the time taken to drop is 8.13secs

Answer:

if your going 15000 mph all you can do is accelerate  or go fast  unless there is a opposite

Explanation:

Given that,

A system dissipates 12 J of heat into the surroundings.

28 J of work is done on the system.

To find,

The internal energy of the system.

Solution,

The first law of thermodynamics is used here. According to this law,

[tex]\Delta E=Q-W[/tex]

Q is heat and W is work done

Here,

Q = -12 J is the heat dissipated by the system

W = -28 J is the work done on the system

ATQ,

[tex]\Delta E=(-12)-(-28)\\\\=-12+28\\\\=16\ J[/tex]

So, the change of internal energy of the system is 16 J.

Answer:

0.27 m/s and 0.01 m/s

Explanation:

Given that

Mass of the bullet, m = 3 g = 0.003 kg

Velocity of the bullet, v = 230 m/s

Weight of the rifle, w = 25 N

From this, we know that the mass of the rifle, M = 25/9.8 = 2.55 kg

Using the law of conservation of momentum, we know that

Momentum of the gun = momentum of the bullet

M.g * V.g = m.b * v.b

2.55 * V.g = 0.003 * 230

2.55V.g = 0.69

V.g = 0.69 / 2.55

V.g = 0.27 m/s

If weight of the shooter = 650, then his mass = 650/9.8 = 66.33 kg

The recoil speed of the shooter is

0.69 / 66.33 = 0.010 m/s

Answer:

F = -4/5 W

Explanation:

We will do this exercise in parts, let's start with the data, The ball must be in balance

            B -W = 0

             B = mg                    (1)

where the thrust is given by Archimedes' principle

            B = ρ g V_liquid

In the problem we are told that the volume of the submerged body is 1/5 of the volume of the body, let's use the subscript 2 for the ball and the subscript 1 for the liquid

            V₁ = [tex]\frac{1}{5}[/tex] V₂

if we use the concept of density for the body

            ρ₂ = m / V₂

            m = ρ₂ V₂

We can see that mass and volume are directly proportional, so we can use a rule of three to find the submerged mass. If mass M is in volume V₂ what mass is there in volume V₂ /5

             m₂ = [tex]\frac{V_{2} }{5} \frac{M}{V_{2} }[/tex]

             m₂ = M / 5

we substitute in equation 1

             B = M / 5 g

This is the thrust that is an upward vertical force, therefore to submerge the whole ball we must apply a downward vertical force equal to the rest of the weight, the equilibrium condition in this case is

             B -W - F = 0

             F = B -W

             F = [tex]\frac{M}{5}[/tex] g - M g

             F = -4/5 Mg

             F = -4/5 W

The negative sign indicates that the force is vertical down

Answer:

16921

Explanation:

Usually, if and when the truck does lose part of its load, or load gets cut into half, then it's momentum gets reduced to half of the original momentum. This is because, from the definition of momentum, we understand that it's the multiplication of mass and velocity. This means that if the mass gets reduced to half, then the total momentum goes ahead to be reduced to half just as well.

New momentum = 1/2 * 33842

New momentum = 16,921 kg∙m/s.

Answer:

Inductive reactance is 50.00 ohms

Explanation:

Given the following data;

Voltage = 120v

Frequency = 60Hz

Current = 2.4 A

To find the inductive reactance;

Inductive reactance, XL = V/I

Where;

Substituting into the equation, we have;

XL = 120/2.4

XL = 50.00 ohms