when scientists publish experimental results their results are often criticized by other scientists how is this process a source of strength of Science? It encourages scientists to give convincing evidence for the results
it allows scientists to keep their data secret
a scientific model is not used full unless everyone thinks it's true
or if forces scientists to publish results that are in line with current theories ​

Answer:

80 Percent

Explanation:

E=energy output/energy input×100

E=8000/10000×100

E=0.8×100

E=80 percent.

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If the machine put, in 8000 J, and the user puts 10,000 J of work then the efficiency of the machine will be equal to 80%.

Work is a physics term used to describe the transfer of energy that takes place when an object changes above a distance because of an external force, at least some of which is given in the vector of the dislocation. The element of the force acting all along the path multiplied by the length of the path can be used to calculate work if the force is constant.

Mathematically, this idea is expressed as W = fd, where W is the effort and f is the force multiplied by d, the distance. Work is completed whenever the force is applied at an angle with about the displacement.

As per the data provided in the question,

Total input energy = 10,000 J

Total output energy = 8,000 J

Then, the efficiency (η) of the machine will be,

η = (output energy/input energy) × 100

η = 8000/10000 × 100

η = 80%.

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Answer:

A. Sliding friction

Explanation:

Sliding friction is weaker than static friction

Answer:

Rolling Friction

Explanation:

I know this because the definition of rolling friction is : type of friction that happens when one body rolls over another

Answer: It will not regain its shape, because when it is corked it can not replace the volume of material that you just take out of it.

Explanation:

When you squeeze the bottle, you are changing the volume of the bottle, in this process, you are "expelling" the material inside the bottle.

When you stop squeezing, there is a change in pressure, and the bottle "absorbs" air, until the pressure is equilibrated, and in this process, the bottle returns to the original shape.

Now, if you take the sauce out of the bottle and immediately cored it, then you removed the material inside of the bottle and did not let the bottle to "refill" the empty space with air, so it can not regain its shape.

Answer:

(a) The package lands 682 meters horizontally ahead from the point the package was dropped from the plane

(b) The horizontal component = 39.0 m/s

The vertical component = 171.55 m/s

(c) The angle of impact is 77.19°

Explanation:

The parameters given are;

Velocity of the plane, vₓ = 39.0 m/s

Height of the plane above the ground, h = 1.50 × 10² m = 1,500 m

(a) The time, t, before the package hits the ground when dropped from the plane is given by the relation;

h = u·t + 1/2×g×t²

Where:

g = Acceleration due to gravity = 9.81 m/s²

u = Initial vertical velocity = 0 m/s

Hence;

1500 = 0×t + 1/2 × 9.81 × t² = 4.905·t²

∴ t = √(1500/4.905) = 17.49 s

The horizontal distance the package travels before landing = 17.49 × 39 ≈ 682 m

The package lands 682 meters horizontally ahead from the point the package was dropped from the plane

(b) The vertical velocity, [tex]v_y[/tex], of the package just before landing is given by the relation;

[tex]v_y[/tex]² = u² + 2·g·h

u = 0 m/s

∴ [tex]v_y[/tex]² = 0 + 2×9.81×1500 = 29430 m²/s²

[tex]v_y[/tex] = √29430  = 171.55 m/s

Hence the horizontal component = 39.0 m/s

The vertical component = 171.55 m/s

(c) The angle of impact, θ, is given as follows;

[tex]tan \theta = \dfrac{v_y}{v_x} = \dfrac{171.55}{39.0 } = 4.4[/tex]

∴ θ = tan⁻¹(4.4) = 77.19°.

Answer:

P.E.=600Nm

Explanation:

m=30kg

g=10m/s²

h=2m

P.E.=?

as we know that

P.E.=mgh

P.E.=30kg×10m/s²×2m

P.E.=600Nm

Answer:

The electric flux through the sphere is [tex]8.58 *10^{5} \frac{Nm^2}{C}[/tex]

Explanation:

Given

[tex]Radius,\ r = 0.03m\\Charge,\ q =7.6\µC[/tex]

Required

Find the electric flux

Electric flux is calculated using the following formula;

Ф = q/ε

Where ε is the electric constant permitivitty

ε [tex]= 8.8542 * 10^{-12}[/tex]

Substitute ε [tex]= 8.8542 * 10^{-12}[/tex] and [tex]q =7.6\µC[/tex]; The formula becomes

Ф = [tex]\frac{7.6\µC}{8.8542 * 10^{-12}}[/tex]

Ф = [tex]\frac{7.6 * 10^{-6}}{8.8542 * 10^{-12}}[/tex]

Ф = [tex]\frac{7.6}{8.8542} *\frac{10^{-6}}{10^{-12}}[/tex]

Ф = [tex]\frac{7.6}{8.8542} *10^{12-6}}[/tex]

Ф = [tex]0.85834970974 *10^{12-6}}[/tex]

Ф = [tex]0.85834970974 *10^{6}}[/tex]

Ф = [tex]8.5834970974 *10^{5}}[/tex]

Ф = [tex]8.58 *10^{5} \frac{Nm^2}{C}[/tex]

Hence, the electric flux through the sphere is [tex]8.58 *10^{5} \frac{Nm^2}{C}[/tex]

Answer:

The second knife-edge must be placed 46.2 cm from the zero mark of the rod.

Explanation:

From the law of equilibrium, ΣF = 0 and ΣM = 0.

Let R be the reaction at the knife edge. Since the weight of the rod and zinc load act downward, and we take downward position as negative

-32 N - 2 N + R = 0

-34 N = -R

R = 34 N

Also, let us assume the knife-edge is x cm from the zero mark. Taking moments about the weight and assuming the knife-edge is right of the weight of the rod. Taking clockwise moments as positive and anti-clockwise moments as negative,

-(45 - 25)2 + (x - 45)R = 0

-(20)2 + (x - 45)34 = 0

-40 = -(x - 45)34  

x - 45 = 40/34

x - 45 = 1.18

x = 45 + 1.18

x = 46.18 cm

x ≅ 46.2 cm

The second knife-edge must be placed 46.2 cm from the zero mark of the rod.

Answer:

A ( Jack did twice as much work as Jill

Explanation:

Answer: A

Heat engine

Explanation: just took the test

Answer:

A. 16t2 -116t -101=0 B. 8.0s

Explanation:

Known parameters from the question:

Height of Cliff,h0 = 101ft

Velocity of rocket ,v= 116ft/s.

1.Substituting the above to the above formula we have;

h(t) = -16t2 + vt + h0

Since h(t) =0, it means the rocket is falling towards the ground, when it gets to the ground when it's at rest the height h(t) = 0m

{Note the rocket is launched from the height of the Cliff so that would be the initial height of the rocket,h0}

2.Substituting into h(t) = -16t2 + vt + h0

We have;

0 = -16t2 + 116t + 101=> 16t2 -116t -101=0

Using formula method for solving quadratic equation we have;

t = -(-116)+_√[(-116)^2 -( 4× 16 ×-101]/ (2× 16)

t = [116 +_(141.1382)]/32

t = (116 -141.1382)/32 or (116 +141.1382)/32

-0.786s or 8.036s

-0.8s or 8.0s to the nearest tenth.

Now time cannot be negative in real life situation hence the time is 8.0s

Note : the general equation of a quadratic equation with variable t is given below;

at2 + bt + c=0

Formula method for quadratic equation is :

t =( -b+_√[(b^2 -( 4× a×c)] ) / (2× a)

Answer:

K is the spring/elastic constant measured in Newton per metre square (N/m²)

Explanation:

E = ½Ke²

In the equation above,

E is the energy in Joules (J)

K is the elastic/spring constant in Newton per metre square (N/m²)

e is the extension in metre (m)

Answer:

In the equation Ee = ½ × k × e², "k" = spring constant

Explanation:

Answer:

space , small amount of gravity is found in the space ,infact we can say that there is no gravity in the space

Answer:

Poles

Explanation:

The gravitational force is maximum at the equator and minimum at the poles.

Answer:

Explanation:

Sounds travel faster in object having high density proportion or matter. This is because particles vibrates and causing the other particle near to as well vibrate. Hence, when sound is moving from a higher dense medium like Water, the rate of traveling is high compare to it moving in air with less dense.

Answer:

51 miles/hour

Explanation:

Talia is on a road trip with some friends. in the first 2 hours, they travel 100 miles. then they hit traffic and go only 30 miles in the next hour. the last hour of their trip, they drive 75 miles. calculate the average speed of talia’s car during the trip. give your answer to the nearest whole number.

The average speed would be 51 miles/hour.

The average speed of a moving object is defined as the total distance traveled relative to the total time taken fro the journey. Mathematically, it is given as:

  total distance traveled/total time taken.

In this case;

Total distance traveled = 100 + 30 + 75 = 205 miles

Total time taken = 2 + 1 + 1 = 4 hours

Therefore;

Average speed = 205/4 = 51.25 miles/hour

To the nearest whole number = 51 miles/hour

Answer:

During charging by conduction, both objects acquire the same type of charge. If a negative object is used to charge a neutral object, then both objects become charged negatively. ... In this case, electrons are transferred from the neutral object to the positively charged rod and the sphere becomes charged positively.

Answer:

B. 4.9 m/[tex]s^{2}[/tex]

Explanation:

The parallel vector, [tex]F_{g}[/tex], make the box to accelerate down the plane due to the presence of an unbalanced force.

The perpendicular component of the force will balance the normal force because the box can not accelerate perpendicularly to the plane.

i.e  [tex]F_{N}[/tex] = [tex]F_{g}[/tex]

Since the box slides down the ramp, neglecting friction and air resistance;

[tex]F_{g}[/tex] = ma

mg Sinθ = ma

But; m = 80 kg, θ = [tex]30^{0}[/tex], g = 9.8 m/[tex]s^{2}[/tex]

80 × 9.8 × Sin [tex]30^{0}[/tex] = 80 × a

784 × 0.5 = 80 a

  392 = 80 a

a = [tex]\frac{392}{80}[/tex]

   =  4.9

Thus, the box accelerates down the ramp at 4.9 m/[tex]s^{2}[/tex].

Answer:

b

Explanation:

b

Answer:

The answer is Pascal or Pa.

Answer:

Pa or small p

Explanation:

Force over Area. The SI unit is Pascal

Answer:

[tex]T_{m }[/tex] = 4.86 s

[tex]T_{e}[/tex] = 1.98 s

Explanation:

Given:

Length = l = 1 m

Acceleration due to gravity of moon = [tex]g_{m}[/tex] = 1.67 m/s²

Acceleration due to gravity of Earth = [tex]g_{e}[/tex] = 10 m/s²

Required:

Time period = T = ?

Formula:

T = 2π [tex]\sqrt{\frac{l}{g} }[/tex]

Solution:

For moon

Putting the givens,

T = 2(3.14) [tex]\sqrt{\frac{1}{1.67} }[/tex]

T = 6.3 [tex]\sqrt{0.6}[/tex]

T = 6.3 × 0.77

T = 4.86 sec

For Earth,

Putting the givens

T = 2π [tex]\sqrt{\frac{1}{10} }[/tex]

T = 2(3.14) [tex]\sqrt{0.1}[/tex]

T = 6.3 × 0.32

T = 1.98 sec

Answer:

The observed temperature was 10º Celsius or 50º Fahrenheit.

Explanation:

The traveler observed that the temperature in Fahrenheit is five times the value of the temperature in Celsius, therefore:

[tex]F = 5*C[/tex]

A Fahrenheit temperature relates to a Celsius one by the following expression:

[tex]F = \frac{9}{5}*C + 32[/tex]

Using the second expression on the first, we can solve for the temperature in Celsius, this is done below:

[tex]\frac{9}{5}*C + 32 = 5*C\\\frac{9}{5}*C - 5*C = -32\\\frac{9*C - 25*C}{5} = -32\\\frac{-16*C}{5} = -32\\-16*C = -32*5\\-16*C = -160\\C = \frac{-160}{-16} = 10\º\text{C}\\F = 5*C = 5*10 = 50\º\text{F}[/tex]

The observed temperature was 10º Celsius or 50º Fahrenheit.

Answer:

Infinity = Never ending

Explanation:

The universe could be infinite, both in terms of space and time, but there is currently no way to test whether it goes on forever or is just very big. The part of the universe we are able to observe is finite, measuring about 46 billion light years in diameter.

The set of natural numbers is an infinite set. This kind of infinity is, by definition, called countable infinity. All sets that can be put into a bijective relation to the natural numbers are said to have this kind of infinity. This is also expressed by saying that the cardinal number of the set is aleph-naught (ℵ0).

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STARS ARE INFINITE , NUMBERS ARE INFINITE

Explanation:

Answer:

8.31 m3-Pa/mol-K

Explanation:

Answer:

7.22 m³ of water should be stored behind the hydroelectric dam.

Explanation:

First we find the total energy that can be stored in the battery. For that purpose we use the formula:

P = VI

where,

P = Power delivered by battery

V = Voltage of Battery = 12 volts

I = Current in Battery

Multiplying both sides by time interval (t), we get:

Pt = VIt

where,

Pt = (Power)(Time) = Total Energy Stored in Battery = E = ?

It = Current Rating of Battery = (50 A.min)(60 s/min) = 3000 A.s

Therefore,

E = (12 volt)(3000 A.s)

E = 36000 J

Now, we have to find the energy required to fully charge the battery:

Energy Required = ΔE = Total Energy Capacity(E) - Already Stored Energy

ΔE = 36000 J - 600 J

ΔE =  35400 J

Now, this energy must be equal to the potential energy of water stored behind hydroelectric dam to fully charge the battery, provided that the conversion efficiency is 100 %.

Therefore,

ΔE = mgh

where,

m = mass of water behind hydroelectric dam

g = 9.8 m/s²

h = height of dam = 50 cm = 0.5 m

Therefore,

35400 J = m(9.8 m/s²)(0.5 m)

m = (35400 J)/(4.9 m²/s²)

m = 7224.5 kg

Now, to find the volume of stored water, we use:

ρ = m/V

V = m/ρ

where,

ρ = density of water = 1000 kg/m³

V = Volume of water behind dam = ?

V = (7224.5 kg)/(1000 kg/m³)

V = 7.22 m³

Answer:

102000N/m2

This is the same as 102KN/m2 (where K = 10^3):

Explanation:

The expression 750 mmHg means 750 height the atmospheric pressure will cause mercury to be suspended due to gravity.

If we brought another fluid under investigation under the influence of the atmospheric pressure the height would be different)

Note that 750 mmHg would be the same as 750/1000 m Hg ( when we convert the mm to m)

0.75mHg

Now to get the pressure in N/m2.

We multiply the height of mercury by the density by the acceleration due to gravity.

This is expressed mathematically thus;

H×d × g ; let d- denote density

Hence we have;

H×d × g = 0.75 × 13600 × 10= 102000N/m2;

Now let's look at the flip.side assuming you don't know the formula for what you require you could use the idea of Unit derivation ;

The unit of interest is N/m2

The unit of height is m

The unit of density is kg/m3

The unit of g is Nkg-1

We would observe if we multiply

m × N/Kg × Kg/m3

We would have (m× N × Kg)/(kg×m3)

Kg cancels out, m cancels out one m from me remaining m2.

Hence our unit becomes N/m2

Note : the unit for density is wrongly expressed remember density is Mass/ volume and their units are respectively kg/m3

The atmospheric pressure on a particular day was measured as 750 mm of Hg. this would be in 102000 N/m²  ( By Assuming the density of

mercury is 13600 kg/m3 and g =10Nkg-1

The total applied force per unit of area is known as the pressure.

The pressure depends both on externally applied force as well the area on which it is applied.

The mathematical expression for the pressure

Pressure = Force /Area

the pressure is expressed by the unit pascal or N /m²

As given in the problem The atmospheric pressure on a particular day was measured as 750 mm of Hg.

Atmospheric pressure is measured by the formula

P = ρgh

where ρ is the density of the mercury

g is the acceleration due to gravity

h is the height of the liquid

By substituting the respective values

P = 13600*10*(750/1000)

P = 102000 N/m²

Thus, the atmospheric pressure would be 102000 in N/m².

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Answer: 0.326kg

Explanation:

Given the following :

Mass of copper (Mc) = 253g

Initial temperature of copper (t1) = 85°C

Mass of aluminium(Ma)=?

Initial temperature of aluminum(t1) = 5°C

Specific heat capacity of aluminum(Ca) = 900

Specific heat capacity of copper (Cc) = 387

Final temperature(t2) = 5°C

Q = mc(t2 - t1)

Ma × Ca × (t2 - t1)a = Mc × Cc × (t2 - t1)c

Ma × 900 × (25 - 5) = 0.253 × 387 × (25 - 85)

Ma × 900 × 20 = 0.253 × 387 × 60

Ma × 18000 = 5874.66

Ma = 5874.66 / 18000

Ma = 0.32637

Ma = 0.326kg

The mass of the aluminum chunk dropped into the water is 325.5 g.

The given parameters;

Apply the principle of conservation of energy, the heat gained by the aluminum is equal to heat lost by the copper;

[tex]M_a C_a (t- t_a) = M_c C_c (t_c - t)\\\\M_a\times 0.9 \times (25-5) = 253 \times 0.386 \times (85-25)\\\\18 M_a = 5859.48\\\\M_a = \frac{5859.48}{18} \\\\M_a = 325 .5 \ g[/tex]

Thus, the mass of the aluminum chunk dropped into the water is 325.5 g.

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Answer: 0.3m

Explanation:

Given the following :

Speed of radio wave(V) = 3 × 10^8 m/s

If 1M = 10^6

Frequency(F) = 90MHz = 90 × 10^6

Wavelength (λ) =?

Speed of wave (V) = frequency(F) × wavelength(λ)

V = fλ

(3 × 10^8) = (90 × 10^6) × λ

λ = (90 × 10^6) / (3 × 10^8)

λ = 30 × 10^(6 - 8)

λ = 30 × 10^-2

λ = 0.3m

Answer:

10 m

Explanation:

Trabajo (W) = 3500 J,   peso de la cuchara (F) = 350 N.

El trabajo es el producto de la fuerza que actúa sobre un objeto y la distancia o desplazamiento. La unidad de trabajo estándar son los joules (J).

Trabajo (W) =  fuerza (F) × distancia (d)

W = F × d

[tex]d=\frac{W}{F} =\frac{3500J}{350}=10m[/tex]

el cubo se elevó a 10 m

The height (distance) to which the bucket was raised is equal to 10 meters.

Given the following data:

To determine the height (distance) to which the bucket was raised:

Mathematically, work done is given by the formula:

[tex]Work\;done = Force \times distance[/tex]

Substituting the given parameters into the formula, we have;

Note: Force = weight.

[tex]3500 = 350 \times distance\\\\Distance = \frac{3500}{350}[/tex]

Distance = 10 meters.

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Answer:

The water particles move in the same direction as the vibrating source of the sound wave. ... What best describes the waves produced by the tuning fork? mechanical, because the vibrating tuning fork makes air molecules around it vibrate. A wave is produced in a Slinky as shown.

Explanation:

Answer:

mechanical, because the vibrating tuning fork makes air molecules around it vibrate

Explanation:

Answer:

Solar panels have increased in efficiency over the past 20 years

Explanation:

Because if efficiency have increased other technologies will be discovered

Answer:

Solar panels have increased in efficiency over the past 20 years

Explanation:

Answer:

A resistor is a battery

Answer:

The answer is A

Explanation:

A resistor is a light bulb because it is the flow of an electric current in an electric circuit.

Answer:

The Event Horizon Telescope comprises of a an interconnection of radio observatories. These radio observatories work in unison and helps in efficient observation of radio sources associated with black holes with angular resolution in comparison to their event horizons. This equipment functions by ensuring that anything or light which goes through the event horizon cannot escape from the black hole. Instead there will be a continual falling towards the center of the black hole.