A radioactive sample has a half-life of 10 min. what fraction of the sample is left after 40 min?

Answer:

b

Explanation:

The magnitude of the net electric field at the center of the square is zero.

When three equal negative point charges are placed at three corners of a square, the forces exerted by the charges cancel each other out at the center of the square, resulting in a net electric field of zero.

Each negative charge creates an electric field that points radially away from it. At the center of the square, the electric fields from the three charges will have equal magnitudes but opposite directions. Due to the symmetry of the system, the vectors representing the electric fields will cancel each other out, resulting in a net electric field of zero.

This cancellation of electric fields at the center of the square is a consequence of the equal magnitudes and positioning of the charges. If the charges were not equal or if they were not positioned symmetrically, the net electric field at the center of the square would not be zero.

In summary, the presence of three equal negative point charges at the corners of a square leads to the cancellation of electric fields at the center, resulting in a net electric field of zero.

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The critical depth in the hydraulic jump can be calculated using the specific energy equation. In this case, with a flow rate of 1.17 m³/s, channel width of 1.7 m, and a depth of 149 mm, the critical depth can be determined.

To calculate the critical depth in the hydraulic jump, we can use the specific energy equation, which relates the flow rate, channel dimensions, and water depth. The equation can be written as:

E = (Q² / (2g)) + (y² / (2g)) + (A² / (P * g))

Where:

E is the specific energy,

Q is the flow rate,

g is the acceleration due to gravity,

y is the water depth,

A is the cross-sectional area of flow,

P is the wetted perimeter of the channel.

In this case, we have a flow rate of 1.17 m³/s, a channel width of 1.7 m, and a depth of 149 mm (or 0.149 m). We need to find the critical depth, which occurs at the hydraulic jump. At the critical depth, the specific energy reaches its minimum value.

To determine the critical depth, we need to set the derivative of the specific energy equation with respect to the water depth equal to zero and solve for y. This will give us the critical depth. However, calculating the critical depth requires knowing additional parameters such as the cross-sectional area and wetted perimeter, which are not provided in the given information. Without these values, it is not possible to calculate the critical depth accurately.

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The force F3→ that will keep the particle in equilibrium is: F3→ = -29 N i^ + 7.5 N j^.

By summing the forces in the x and y directions and taking the negative of their sum, we can determine the force F3→ that will balance the applied forces and keep the particle in equilibrium.

To keep the particle in equilibrium, the net force acting on it must be zero. This means that the sum of the forces in the x-direction and the sum of the forces in the y-direction must both be zero.

F1→ = 11 N i^ - 5 N j^

F2→ = 18 N i^ - 2.5 N j^

To find the force F3→ that will keep the particle in equilibrium, we need to find the negative of the vector sum of F1→ and F2→.

Summing the forces in the x-direction:

F1x = 11 N

F2x = 18 N

F3x = -(F1x + F2x) = -(11 N + 18 N) = -29 N

Summing the forces in the y-direction:

F1y = -5 N

F2y = -2.5 N

F3y = -(F1y + F2y) = -(-5 N + (-2.5 N)) = 7.5 N

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The value that we get by solving the equation is 3. This we get by solving the equation and with the help of given values of u and t.

In mathematical formulas, the equals sign is used to indicate that two expressions are equal. The meaning of the word equation and its cognates might vary slightly depending on the language. For example, an equation in English is defined as any properly expressed formula that consists of two expressions connected by the equals sign, whereas an equation in French is defined as having one or more variables.

According to the question, the given values are :

u = 11 and,

t = 9.

The given equation is :

3 + 11 t - 9 u

Substitute the given values of u and t in the equation :

3 + 11 (9) - 9 (11)

= 3

Hence, after solving the equation, the value we get is 3.

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The repeated flying into the air and landing on the same spot reinforces to the woodcock that this is the center of its territory.

The phrase "Woodcock sky dances" refers to the woodcock's breeding routine. It is a migratory bird that mates in the United States' Eastern and Central regions. Woodcock "sky dances" or courtship flights, which are a part of its breeding ritual, are familiar to ornithologists and bird lovers.The male woodcock prepares for the display by choosing a place and then creating a tiny opening in the trees or shrubs. It flies into the air at sunset or sunrise, calling out with a distinctive chirping sound. It then lands on the same spot, with each flight being more extensive than the last. The woodcock does this repeatedly, with each flight reaching a greater height than the previous one.

The woodcock's territory is at the center of its sky dancing. The repeated flying into the air and landing on the same spot reinforces to the woodcock that this is the center of its territory. During the breeding season, the woodcock's sky dancing activity is essential. It shows off the male's strength and agility to female woodcocks, which aids in their selection of mates.The woodcock's behavior is a result of natural selection. Through sky dancing, the woodcock's species has developed its breeding ritual over thousands of years. The ability to perform sky dances is an evolutionary benefit to the woodcock, as it aids in species reproduction and survival. Therefore, repeatedly flying into the air and landing on the same spot reinforces to the woodcock that this is the center of its territory.

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Answer:

Because the sodium bicarbonate does not separate into sodium, hydrogen, carbon and oxygen

Explanation:

The components of sodium bicarbonate differ in their solubilities in water.baking soda is sodium bicarbonate.

Using observations of the atomic hydrogen 21 cm line rotation curves of spiral galaxies determined beyond radii where starlight can be detected.

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Answer: The total current through the parallel combination of the diodes is: 3.90 μA

Explanation: Assuming the diodes are ideal with an offset voltage of Vf, the current-voltage characteristic of a single diode is given by:

i = 0 for v < -Vf (diode off)

i = I_s * (exp(v / (n * Vt)) - 1) for v >= -Vf (diode on)

where I_s is the saturation current, n is the diode ideality factor, and Vt is the thermal voltage.

Since the diodes are in parallel and opposing, one of them will be reverse-biased and the other will be forward-biased. The reverse-biased diode will have no current flowing through it, so we only need to consider the forward-biased diode.

Let's assume that d1 is forward-biased and d2 is reverse-biased. Then the voltage across d1 is V and the voltage across d2 is -V. The total current through the parallel combination of the diodes is the sum of the currents through each diode:

i = i1 + i2 where i1 is the current through d1 and i2 is the current through d2. Since d2 is reverse-biased, we have i2 = 0. The current through d1 is given by:

i1 = I_s * (exp(V / (n * Vt)) - 1)

To find V, we use the fact that the total current i is equal to the current through a resistor R in series with the diodes:

i = (V - (-V)) / R

i = 2V / R

Setting these two expressions for i equal to each other, we get:

I_s * (exp(V / (n * Vt)) - 1) = 2V / R

This is a transcendental equation that cannot be solved analytically. However, we can use numerical methods (e.g., Newton-Raphson) to find the solution. For simplicity, let's assume that the diodes are identical, so I_s and n are the same for both diodes. Then we can write:

I_s * (exp(V / (n * Vt)) - 1) = V / (2R)

Let's define a dimensionless variable x = V / (n * Vt). Then the equation becomes:

I_s * (exp(x) - 1) = x / (2nR * Vt)

Using the values given in the problem (I_s = 10^-15 A, n = 1, Vt = 25.85 mV, R = 1 kΩ), we can solve for x numerically:

x ≈ 2.145

Then the voltage across the diode is:

V = x * n * Vt ≈ 55.7 mV

Since this voltage is much smaller than the offset voltage of Vf = 0.7 V, we can assume that both diodes are on. The current through each diode is:

i1 = i2 = I_s * (exp(V / (n * Vt)) - 1) ≈ 1.95 μA

Therefore, the total current through the parallel combination of the diodes is:

i = i1 + i2 ≈ 3.90 μA

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Answer:

30 m\ s Ans .....

Explanation:

Data:

f = 10 Hz

w = 3 m

v = ?

Formula:

v = fw

Solution:

v = ( 10)(3)

v = 30 m\ s Ans ........

The acceleration of the cart is 3.71m/s².

Acceleration refers to the rate of change of the velocity of an object with respect to time. It is measured in m/s².

The acceleration of a body can be calculated by dividing the force by the mass as follows:

Acceleration = Force ÷ mass

According to this question, a 16.0 kg cart is being pulled by a 95.4 N force to the right, and a 36.0 N force to the left.

The net force = 95.4N - 36.0N = 59.4N

Acceleration = 59.4N ÷ 16kg = 3.71m/s²

Therefore, 3.71m/s² is the acceleration of the cart.

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Answer: Exothermic

Explanation:

An exothermic reaction causes an increase in temperature. This is because the energy released when the bonds are broken among the reactants is greater than than the energy absorbed when new bonds are formed among the products. This leftover energy gets passed along to the surroundings, where it produces a measurable increase in heat.

Answer: These forces are an example of newtons third law every action has equal and opposite reaction

Explanation:UwU

A baseball player launches a big home run to start the game. The ball leaves the bat with a speed of 40.0 m/s and an angle of 30.0° from the horizontal.

An item or particle that is propelled into a gravitational field, for example from the surface of the Earth, and moves across a curved route only under the influence of gravity is said to be experiencing projectile motion. Most calculations make the assumption that the effects of air resistance are passive and insignificant in the specific instance of Earth projectile motion. The curving path of objects in projectile motion was proved by Galileo to be a parabola, but it could also be a straight line in the specific situation when it is hurled directly upwards. One such trajectory is a ballistic trajectory, which is the study of such motions.

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Answer:

the gravity was pulling the cup to the front of the window even though the wind was pushing it the other way.

Explanation: the gravity must be strong

By using the Newton's first law of Motion, it can be explained why the coffee spilt all over the windshield. This is because there is gravitational force which acts upon it and it pushes the substances in the downward direction towards the Earth.

Newton's first law of Motion states that a body remains in the same state of rest or uniform motion in a straight line unless and until an external force is applied on it. This means that a body will not start moving by itself until and unless an external force acts on it.

In this case, lachance's daughter is trying to pick her coffee cup, the coffee cup at the windshield is spilt which makes it difficult for her to see. This is because, there is the gravitational force or gravity which is pulling the coffee cup to the front of the window even though the wind was pushing it in the other way.

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Answer:

The train's acceleration is 4.5 m/s²

Explanation:

The train's speed increased by 45 m/s after 10 seconds, which means that it's speed increased by 4.5 m/s each second, or rather 4.5m/s²

P1 x v1/t1 = p2 x v2 / t2

use the given values:

1.5 x 106 / 318 = 2 x v2 / 293

Simplify:

0.5 = (2 x v2)/293

Multiply both sides by 293:

146.5 = 2 x v2

Divide both sides by 2:

V2 = 73.25 L

Answer: 73.25 L

Answer:

False

Explanation:

Transpiration is a form of Evaporation, but it only applies to plants whereas evaporation can apply to all liquids.

A centrifuge is a device in which a small container of material is rotated at a high speed on a circular path: The sample is making approximately 278 revolutions per minute.

To determine the number of revolutions per minute the sample is making, we need to relate the centripetal acceleration, radius, and angular velocity.

Centripetal acceleration (a_c) is related to the radius (r) and angular velocity (ω) by the formula: a_c = rω².

Given that the centripetal acceleration of the sample is 7.98 x 10³ times the acceleration due to gravity (g), we can write: a_c = 7.98 x 10³g.

We know that the acceleration due to gravity is approximately 9.8 m/s².

Substituting the values, we have: 7.98 x 10³g = rω².

Rearranging the equation to solve for ω, we get: ω = sqrt((7.98 x 10³g) / r).

The radius is given as 6.07 cm, which is 0.0607 m.

Substituting the values, we find: ω = sqrt((7.98 x 10³ * 9.8) / 0.0607).

Calculating this expression, we find ω ≈ 511.26 rad/s.

To convert this angular velocity to revolutions per minute, we can use the conversion factor: 1 revolution = 2π radians.

Thus, the number of revolutions per minute is approximately ω / (2π) * 60, which is approximately 278 revolutions per minute.

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The mass of the object is approximately 2.04 kg.

To find the mass of the object, you can use Hooke's Law, which states that the force exerted by a spring is proportional to its displacement (F = kx). In this case, the spring constant (k) is 40 N/m and the displacement (x) is 0.5 m.
1. Calculate the force exerted by the spring:

F = kx

= 40 N/m × 0.5 m

= 20 N
2. Since the force exerted by the spring is equal to the gravitational force acting on the object (F = mg), you can solve for the mass (m) using the acceleration due to gravity (g), which is approximately 9.81 m/s².
3. Rearrange the formula to solve for mass:

m = F/g

= 20 N / 9.81 m/s²

≈ 2.04 kg
The mass of the object is approximately 2.04 kg.

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Radio waves traveling through the ionosphere at high latitudes experience quick and unpredictable oscillations, which is known as high-latitude scintillation.

The auroral border, or area of the ionosphere where the aurora borealis (northern lights) appear, is typically connected with scintillation. However, high-latitude scintillation can occasionally be seen equatorward of the auroral boundary depending on the circumstances. The cause of this phenomenon is the presence of ionospheric irregularities that go beyond the auroral oval, such as irregularities in plasma density brought on by equatorial spread F (ESF). ESF can produce significant ionosphere-wide anomalies that lead to scintillation at lower latitudes. This may occur when the sun is active more intensely or when particular ionospheric circumstances favor the production of these anomalies.

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D.

They don't have directions.

The quantities with only magnitude and no direction are called scalar quantities. Therefore, option D is the correct answer.  

Scalar quantities have only magnitude but vector quantities have both magnitude and direction. Some examples of scalar quantities are,

• Mass

• Temperature  

• Speed

• Density

Thus, we conclude that the quantities with only magnitude and no direction are scalar quantities. Hence option D is the correct pair.

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At horizontal angles, relative to the original direction of the waves, will be  1.4597 rad and the intensity will be 1.576 W/m².

A radar antenna is a device that sends out radio waves and listens for their reflections. The ability of an antenna to identify the exact direction in which an item is placed determines its performance.

The horizontal angle for the given condition is;

sinθ∝1

sinθ=(nλ)/a

n∝(λ/a)

\(\rm n = \frac{88.9 \times 10^6 \times 15}{3 \times 10^8 } \\\\ n=4.4454\)

\(\rm n_{max}=4\)

The maximum angle is;

\(\rm \theta_4=\frac{4 \times 3 \times 10^8}{15 \times 88.9 \times 10^6 } \\\\ \rm \theta_4=64.14^0\)

The value of the wavelength is;

\(\rm \lambda= \frac{c}{v} \\\\ \rm \lambda= \frac{3 \times 10^8 }{88.9 \times 10^6} \\\\ \lambda= 3.3745 \ m\)

The value of the intensity is;

\(\rm I= I_{max}[\frac{sin \frac{\beta}{2}}{\frac{\beta}{2}} ]\\\\ \frac{\beta}{2} =\frac{\pi}{4} (a sin\theta)\\\\ \beta=\frac{\pi}{3.3745} (15 sin 6^0)\\\\ \beta=1.4597 \ rad\)

\(\rm I = 3.4[ \frac{sin 1.4597}{1.4597} ]^2\\\\ I=1.576 \ W/m^2\)

Hence,at horizontal angles, relative to the original direction of the waves, will be  1.4597 rad and the intensity will be 1.576 W/m².

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The procedure is not found here but a chemical reaction is characterized to be a process where substances are converted into products.

A chemical reaction is a process where one or more reactants are converted into chemical products.

In a chemical reaction, enzymes are molecules that speed up the process by lowering its activation energy.

In conclusion, the procedure is not found here but a chemical reaction is characterized to be a process where substances are converted into products.

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Answer:

Energy = 18.3 Kilowatt-hour

Explanation:

Given the following data;

Power = 1220 Watts

Time = 30 * 30 = 900 minutes to hours = 900/60 = 15 hours

To find the energy consumption;

Power can be defined as the energy required to do work per unit time.

Mathematically, it is given by the formula;

\( Power = \frac {Energy}{time} \)

Making energy the subject of formula, we have;

Energy = power * time

Energy = 1220 * 15

Energy = 18300 Joules

To convert energy to Kilowatt-hour;

Energy = 18300/1000

Energy = 18.3 Kilowatt-hour

From the instant it leaves your hand until it hits the ground, the object's acceleration is 9.8 m/s^2 down.

it doesn't matter whether you throw it up hard, up easy, horizontal, DOWN, or just drop it. Its acceleration is the same, and is constant, in every case.

The evidence for dark matter comes from observations of the gravitational effects it has on visible matter and cosmic microwave background radiation.

The existence of dark matter was first proposed to explain the observed gravitational effects on visible matter, such as stars in galaxies and clusters of galaxies, that could not be accounted for by the visible matter alone. These observations suggested the presence of a large amount of matter that is not visible, hence the term "dark" matter. Additional evidence for dark matter comes from observations of the cosmic microwave background radiation, which is the remnant radiation from the Big Bang. The patterns of the cosmic microwave background radiation suggest that dark matter played a critical role in the formation of the large-scale structure of the universe. While the nature of dark matter is still unknown, its presence is inferred from its gravitational effects on visible matter and radiation.

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The focal length of the lens/cornea system is approximately 17.9 cm.

What is Len?
A lens is indeed a transmissive optical tool that uses refraction to focus or disperse a light beam. A compound lens is made up of multiple simple lenses (elements), typically arranged along a common axis, as opposed to a simple lens, which is one solid piece of transparent material. Glass or plastic are used to make lenses, which are then polished or moulded into the desired shape. In contrast to a prism, which simply refracts light without focusing it, a lens can focus light to create an image. Lenses are also devices that focus as well as disperse waves as well as radiation other than visible light, such as explosive lenses, microwave lenses, electron lenses, and acoustic lenses.

Lenses are a common component of telescopes, binoculars, and cameras, among other imaging devices.

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