At a hydroelectric power plant, water is directed at high speed against turbine blades on an axle that turns an electric generator. For maximum power generation, should the turbine be designed so that the water is brought to a dead stop, or so that the water rebounds? If only an external force can change the momentum of the center of mass of an object, how can the internal force of the engine accelerate a car?

Answer:

10 hours earlier than regular train

Explanation:

In this case you are already giving the expression to be used which is:

S = D/t   (1)

The problem is giving us the data of the speed of both trains, and we also know the distance between City A and B, which is 4000 km, therefore, we just need to solve for t in the above expression for both trains, and then, do the difference between their times and see how much earlier the express train arrives.

Solving for t, we have:

t = D/S   (2)

For Train 1 (The regular):

t₁ = 4000 / 80

t₁ = 50 h

For Train 2 (Express):

t₂ = 4000 / 100

t₂ = 40 h

Now, as expected express train arrives earlier, now let's see how much:

T = t₁ - t₂

T = 50 - 40

Therefore, Express train arrives 10 hours earlier than regular train.

Hope this helps

Answer:

v = 6.95 m/s

Explanation:

Given that,

A diver is on a board 1.80 m above  the water, s = 1.8 m

The initial speed of the diver, u = 3.62 m/s

Let v is the speed with which she hit the water. It will move under the action of gravity. Using the equation of motion as follows :

\(v^2-u^2=2gs\\\\v=\sqrt{u^2+2gs} \\\\v=\sqrt{(3.62)^2+2(9.8)(1.8)} \\\\v=6.95\ m/s\)

So, she will hit the water with a speed of 6.95 m/s.

The potential difference across a cell wall can be calculated using the formula:

ΔV = Ed

where ΔV is the potential difference, E is the electric field strength, and d is the distance or thickness of the cell wall.

Plugging in the values given in the problem, we get:

ΔV = Ed = 360 × 10^-9 × 6.5 × 10^-3 = 2.34 × 10^-6 volts

Therefore, the potential difference across the cell wall is 2.34 microvolts (μV).

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The mysterious sliding stones in Death Valley, California, involve stones moving horizontally along the desert floor, creating prominent trails. To calculate the horizontal force required to maintain the motion of a 20 kg stone once it starts moving, we can use the coefficient of kinetic friction (μk) and the normal force (F_N).

The normal force is equal to the weight of the stone (F_N = mg), where m is the mass (20 kg) and g is the acceleration due to gravity (approximately 9.81 m/s^2). F_N = 20 kg × 9.81 m/s^2 = 196.2 N.

Next, we can calculate the horizontal force (F_H) required to maintain the stone's motion using the formula: F_H = μk × F_N. With a coefficient of kinetic friction of 0.80, we have:

F_H = 0.80 × 196.2 N = 156.96 N.

Thus, a horizontal force of approximately 156.96 N is required to maintain the motion of a 20 kg sliding stone once it starts moving.

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Answer:

10 m/s²

Explanation:

Since the body is falling freely from the rest, it will be having an acceleration equal to the acceleration due to gravity.

∴ Acceleration = g = 9.8 m/s². ≈ 10 m/s².

Answer:

10 m/s^2 I hope it helps u a lot

When three different resistors are connected in series to a battery, the current through all resistors is the same.

In a series circuit, there is only one path for current to flow through. Current is the same through each component.

In a series circuit, the total voltage is divided across each component, and the voltage drop across each component is proportional to its resistance.

The equivalent resistance of the circuit is the sum of all resistors. It is not an algebraic sum, rather it is the arithmetic sum of the resistors. Hence, option A is incorrect.

The other two statements are also incorrect as the voltage on each resistor is not the same, it is divided across each resistor in proportion to its resistance. Therefore, the correct statement about the given circuit is: Currents through all resistors are the same.

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A 0.1mm diameter glass tube is inserted into an ethyl alcohol at 20 degrees centigrade in a cup. The angle of alcohol with the tube is 0 degrees. D = 0.1 mm = 0.001m, alcohol angle is 0 degrees, ethyl alcohol

\(η=1.1×10^-3 N⋅sec/ m², s_g\)

=0.79.

We have to determine how much glycerin rises in the tube. The force that moves the liquid through the tube is the difference between the downward force of gravity on the liquid column and the upward capillary force produced by the surface tension of the liquid against the walls of the tube.

The height to which the fluid rises in a capillary tube may be measured by balancing the capillary force against the force of gravity on the column.

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We know that the energy stored in a parallel-plate capacitor can be expressed as:$$E=\frac{1}{2}CV^2$$where E is the energy in joules (J), C is the capacitance in farads (F), and V is the voltage across the plates in volts (V).Now we can find the electric field inside the capacitor.

Let E be the electric field strength, d be the plate separation, and A be the area of each plate. The capacitance C can be expressed as:

\($$C=\frac{\epsilon_0A}{d}$$\)

where ε0 is the permittivity of free space, which is approximately equal to 8.85 x 10-12 F/m.

Therefore, we have:

\($$C=\frac{\epsilon_0A}{d}$$\)

Rearranging this equation gives:

\($$A=\frac{Cd}{\epsilon_0}$$$$A=\frac{(10×10^{-6})×(12.5×10^{-3})}{8.85×10^{-12}}=1.418×10^{-2}m^2$$\)

Now we can find the electric field inside the capacitor. The potential difference V between the plates can be found using the energy stored in the capacitor. Therefore, we have:

\($$V=\sqrt{\frac{2E}{C}}$$$$V=\sqrt{\frac{2×(8×10^{-3})}{10×10^{-6}}}=\sqrt{16}=4V$$\)

The electric field strength E inside the capacitor can be expressed as:\($$E=\frac{V}{d}=\frac{4}{12.5×10^{-3}}=320V/m$$\)

Therefore, the answer is (B) 320 V/m.

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Answer:

f = 459.8 Hz

Explanation:

When a trumpet is playing it is an open tube at both ends, therefore there is a belly in each one, the resonance occurs to

           λ = 2L             1st harmonic

           λ = 2L /2        2nd harmonic

           λ = 2L /3       3rd harmonic

the speed of the wave is

           v = λ f

           λ = v / f

we substitute in the third harmonic

            \(\frac{v}{f} = \frac{2L}{3}\)            (1)

            L = \(\frac{3}{2} \ \frac{v}{f}\)

            L = \(\frac{3}{2} \ \frac{343}{ 510}\)

            L = 1.009 m

indicates that to  add ΔL = 0.110 m, so the total length is

            L_total = L + ΔL

            L _total = 1.009 + 0.110

            L _total = 1,119 m

we use equation 1

            f =  \(\frac{3}{2} \ \frac{v}{L_{total}}\)

            f = \(\frac{3}{2} \ \frac{343}{1.119}\)

            f = 459.8 Hz

Answer: The Big Bang Theory

Explanation:

Answer:

oxygen and carbon dioxide

Explanation:

are soluble in water animal and plants can utilize these dissolved gases for resporation and photosynthesis and hence can survived in water

The force F1 is equal and opposite to the downward force thus, F1 is equal to 60 N. The force F2 is inclined to 30 ° from leftward force and it is equal to 38.97 N in magnitude.

Force is an external agent acting on a body to deform it or to change its state of motion or rest. Force is a vector quantity and it is characterised by its magnitude and direction.

If two forces acting on a body from the same directions, then the net force will be the sum of these two forces. If they are acting from opposite directions, they will cancel each other in magnitude.

The force F1 is equal and opposite to the force acting downward. Thus its magnitude is 60 N. The force F2 is inclined to 30 ° from horizontal direction.

F2 = 45 cos 30 = 38.9 N.

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The force constant of the spring is obtained as  0.49.

We would have to know that we to look at the Hooke's law which states that if we have an elastic substances , then the magnitude of the stretching would be proportional to the force that is acting on the spring.

Then we have that;

F = Ke

F = force that is acting on the material

e = extension

We would now need to obtain the force constant as follows;

20 * 10^-3 * 9.8 = K * 40 * 10^-2

K = 20 * 10^-3 * 9.8 /40 * 10^-2

K = 0.196/0.4

K = 0.49

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Answer:

either its 12 or 0.402

Explanation:

The object D is made up of material Lead. The correct option is D.

The specific heat is the amount of heat required to change the temperature by 1°C. It is denoted by C.

Two 1-kg objects, C and D, increase in temperature by the same amount, but the thermal energy transfer of object C is greater than the thermal energy transfer of object D. The object C has a specific heat of 235 J/kg-K.

Q = m C ΔT

Qc > Qd

The energy transfer is proportional to specific heat.

Specific heat of D must be less. The possible material with specific heat less than the given value is for Lead material.

Thus, the correct option is D.

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Answer:

The force exerted by the car engine was 3000 N

Explanation:

Mechanical Force

According to the second Newton's law, the net force exerted by an external agent on an object of mass m is:

\(F=m.a\)

Where a is the acceleration of the object.

On the other hand, the equations of the Kinematics describe the motion of the object by the equation:

\(v_f=v_o+a.t\)

Where:

vf is the final speed

vo is the initial speed

a is the acceleration

t is the time

The question describes how Meitner drove home taking her car from rest to a speed of 20 m/s in 10 seconds. This provides us the following data:

vf=20 m/s, v0=0 (rest), t = 10 seconds.

From the kinematics equation, we can solve for a:

\(\displaystyle a=\frac{v_f-v_o}{t}\)

\(\displaystyle a=\frac{20\ m/s-0}{10\ s}=2\ m/s^2\)

The force exerted by the car engine was:

\(F=1500\ kg\cdot 2\ m/s^2\)

\(F=3000\ N\)

The force exerted by the car engine was 3000 N

Answer:

c infections

Explanation:

Answer:

oi

Explanation:

The speed of the wave on a string is given by Taylor's formula:

where

F = tension force

μ = linear density = mass per unit length

But also we can say the speed of any wave is given by:

where:

λ = wave length

f = frequency

Plug the second equation in the first one. We get:

Now solve for f:

Lets say wave length is the same on the second case. Since it's the same string μ will also be the same.

See that 340 N = 2 x 170, so we can write:

Answer:

B. 0.4 N/cm

Explanation:

While stretching a spring 20 cm past its natural length, it exerts a force of 8 N. What is the spring constant of this spring is 0.4 N / cm, the correct option is B.

The spring constant is used to define the stiffness of the spring, the greater the value of the spring constant stiffer the spring and it is more difficult to stretch the spring.

The mathematical relation for calculating the spring constant is as follows

F = - Kx

where F represents the Force

x represents the amount of stretch in the spring

K represents the value of the spring constant

For given problem

F= 8 N and x = 20 cm

K = F/x

   =8/20 N/ cm

   =0.4 N / cm

The spring constant for the spring is 0.4 N/ cm

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The loudness of the sound at the rock concert, where the intensity of the sound is1 x 10⁻¹ Wm⁻² is  110 dB.

Here we are dealing with loudness which is the perception of the Intensity of the sound.

The formula  to refer to in order  to  find the value of the loudness of a sound is ,

  db= 10log(I/I₀)

As we are provided with the current intensity which is  1 x 10⁻¹ Wm⁻². and the initial intensity which is  1 x 10⁻¹² Wm⁻².

So, by substituting the required values in the formula we get

db= 10 * log( 1 x 10⁻¹ /1 x 10⁻¹²)

 = 10 * 11 log(10)

 = 110

So, the result is 110 dB.

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The induced voltage in the second case will be higher but the change in flux will be same in comparison to the first case.

In the experiment of measuring the change of flux and the induced voltage,

In the first case the magnet is dropped from a height 3cm of the coil and in the second case the the magnet is raised so that it drops 20cm before entering the coil.

When compare to the first case the second case will have a higher value of induced voltage but the change in flux will be same.

The induced voltage in a coil is given by,

E = dM/dt

dM is change in magnetic flux,

t is time,

As we can see that the time is inversely proportional to the induced emf and in the second case the magnet is drop from a height which allows it to go with the higher velocity in a less time that is why the induced EMF is more in magnitude but because the magnet is same in both the cases the change in flux is constant.

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The fraction of each hour the heat pump must be running is 1800 J/s / 5400 J/s = 1/3 and the heat pump will cost $15.12 each month.

a) To determine the fraction of each hour the heat pump must be running, we need to consider the rate at which heat leaves the room and the efficiency of the heat pump.
Given that the heat naturally leaves the room at a rate of 1800 J/s, and the heat pump has a coefficient of performance (COP) of 6, we can calculate the rate at which the heat pump is moving heat from outside to inside.
The COP of a heat pump is defined as the ratio of the heat delivered to the input work. In this case, the COP is 6, so for every 1 unit of input work (900 W), the heat pump delivers 6 units of heat.
Therefore, the rate at which the heat pump is moving heat from outside to inside is 900 W * 6 = 5400 J/s.
To maintain a constant room temperature, the rate at which heat leaves the room (1800 J/s) should be balanced by the rate at which the heat pump is moving heat from outside to inside (5400 J/s).
Therefore, the fraction of each hour the heat pump must be running is 1800 J/s / 5400 J/s = 1/3.
b) To calculate the cost of running the heat pump each month, we need to know the cost of electricity and the total energy consumed by the heat pump in kilowatt-hours (kWh).
Given that the heat pump draws 900 W of power, we can calculate the energy consumed by the heat pump in one hour:
900 W * 1 h = 900 Wh = 0.9 kWh
The cost of electricity is given as $0.07/kWh.
To determine the monthly cost, we need to know the number of hours the heat pump runs in a day. Let's assume it runs for 8 hours per day.
Therefore, the energy consumed by the heat pump in a day is 0.9 kWh * 8 = 7.2 kWh.
And the monthly cost of running the heat pump is 7.2 kWh * 30 days * $0.07/kWh = $15.12.
So, the heat pump will cost $15.12 each month.

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Answer:

its false

Explanation:

since the penny is thrown straight up its not going to move forwad with you and the bus since it has no forces pushing on it. If the bus wasn't moving it would land back on your hand

The most effective insulating material is polystyrene.

The material which isolates the body and doesn't allow heat and mass to flow out of the control system.

The insulating material should have the lowest thermal conductivity.

Polystyrene foam has low thermal conductivity which makes it a great insulator to heat.

Aluminum foil can be an effective insulating material because it doesn't flow heat out into the environment.

Cotton wool is effective, but not it is not fire resistant.

Thus, the best effective insulating material is polystyrene.

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The orbital period of the Earth around the Sun is determined by its distance from the Sun and its mass. If the Earth had twice its present mass but orbited at the same distance from the Sun, its gravitational attraction to the Sun would be stronger, resulting in a longer orbital period. Using Kepler's third law of planetary motion, we can calculate the new orbital period as follows:

T^2 = (4π^2/G) x (r^3/m)

where T is the orbital period, G is the gravitational constant, r is the distance from the Earth to the Sun, and m is the mass of the Earth.

Plugging in the values, we get:

T^2 = (4π^2/6.6743 x 10^-11) x [(149.6 x 10^6)^3 / (2 x 5.9722 x 10^24)]
T^2 = 1.085 x 10^20
T = √(1.085 x 10^20)
T = 1.09 x 10^10 seconds

Converting this to years, we get:
T = 346 years

Therefore, if the Earth had twice its present mass but orbited at the same distance from the Sun as it does now, its orbital period would be approximately 346 years.

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Answer:

Because the output force is greater than the input force, the input distance must be greater than the output distance.

Explanation:

The work done by the man against gravity in climbing to the top is 9,480 foot-pounds.

To calculate the work done by the man, we need to determine the total change in potential energy as he climbs up the helical staircase that encircles the silo. The potential energy can be calculated using the formula PE = mgh, where m represents the mass, g represents the acceleration due to gravity, and h represents the height.

In this case, the mass of the man is 190 lb, and the height of the silo is 80 ft. Since the man makes exactly four complete revolutions around the silo, we can calculate the circumference of the helical staircase. The circumference of a circle is given by the formula C = 2πr, where r represents the radius. In this case, the radius of the silo is 15 ft.

To find the work done against gravity, we need to multiply the change in potential energy by the number of revolutions. The change in potential energy is obtained by multiplying the mass, the acceleration due to gravity (32.2 ft/s²), and the height. The number of revolutions is four.

Therefore, the work done by the man against gravity in climbing to the top can be calculated as follows:

Work = 4 * m * g * h

    = 4 * 190 lb * 32.2 ft/s² * 80 ft

    = 9,480 foot-pounds.

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