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The radius of a circular track is 7 m. What will be the speed of a scooter, if it takes 20 seconds to complete one round of the
track?
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A: 2.2 m/s
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B: 22 m/s
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C: 0.22 m/s
D: 022m/s
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24/05/20
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Answer:

D. all of the above

Explanation:

Answer:

Mobility of the minority carriers, [tex]\mu_{n} =1184.21 cm^{2} /V-sec[/tex]

Diffusion coefficient for minority carriers,[tex]D_{n} = 29.20 cm^2 /s[/tex]

Verified from Einstein relation as  [tex]\frac{D_{n} }{\mu_{n} } = 25 mV[/tex]

Explanation:

Length of sample, [tex]l_{s} = 2 cm[/tex]

Separation between the two probes, L = 1.8 cm

Drift time, [tex]t_{d} = 0.608 ms[/tex]

Applied voltage, V = 5 V

Mobility of the minority carriers ( electrons), [tex]\mu_{n} = \frac{V_{d} }{E}[/tex]

Where the drift velocity, [tex]V_{d} = \frac{L}{t_{d} }[/tex]

[tex]V_{d} = \frac{1.8}{0.608 * 10^{-3} } \\V_{d} = 2960.53 cm/s[/tex]

and the Electric field strength, [tex]E = \frac{V}{l_{s} }[/tex]

E = 5/2

E = 2.5 V/cm

Mobility of the minority carriers:

[tex]\mu_{n} = 2960.53/2.5\\\mu_{n} =1184.21 cm^{2} /V-sec[/tex]

The electron diffusion coefficient, [tex]D_{n} = \frac{(\triangle x)^{2} }{16 t_{d} }[/tex]

[tex]\triangle x = (\triangle t )V_{d}[/tex], where Δt = separation of pulse seen in an oscilloscope in time( it should be in micro second range)

[tex]\triangle x = \frac{(\triangle t) L}{t_{d} } \\\triangle x = \frac{180*10^{-6} * 1.8}{0.608*10^{-3} }\\\triangle x =0.533 cm[/tex]

[tex]D_{n} = \frac{0.533^{2} }{16 * 0.608 * 10^{-3} }\\D_{n} = 29.20 cm^2 /s[/tex]

For the Einstein equation to be satisfied, [tex]\frac{D_{n} }{\mu_{n} } = \frac{KT}{q} = 0.025 V[/tex]

[tex]\frac{D_{n} }{\mu_{n} } = \frac{29.20}{1184.21} \\\frac{D_{n} }{\mu_{n} } = 0.025 = 25 mV[/tex]

Verified.

Answer:22 m/s

Explanation:

Given

launch angle [tex]\theta =60^{\circ}[/tex]

height of goal [tex]h=4.55\ m[/tex]

and horizontal distance [tex]x=40\ m[/tex]

Suppose initial speed is [tex]u[/tex]

Trajectory of a Projectile is given by

[tex]y=x\tan \theta -\frac{1}{2}\frac{gx^2}{u^2\cos ^2\theta }[/tex]

substituting the values we get

[tex]4.55=40\tan (60)-0.5\times \frac{9.8\times (40)^2}{u^2\cdot \cos ^260 }[/tex]

[tex]4.55=69.28-0.5\times \frac{15,680}{u^2\cdot 0.25}[/tex]

[tex]\frac{31,360}{u^2}=69.28-4.55[/tex]

[tex]\frac{31,360}{64.73}=u^2[/tex]

[tex]u^2=484.47[/tex]

[tex]u=22.01\ m/s[/tex]

So, initial launch speed is [tex]22\ m/s[/tex]

Answer:

The resultant velocity = 3.16 m/s

Explanation:

Since the boat is moving North of the direction of the riverflow, the river would either be flowing westward or Eastward. The two motions form a right angle triangle with the resultant velocity being the hypotenuse of the traingle.

The resultant velocity will be given as ;

R² = B² + r²

Where B is the velocity of the boat and r is the velocity of the river

R² = 3² + 1²

R² = 10

R = √10 = 3.16 m/s

Therefore, the resultant velocity = 3.16 m/s

Answer:

T =  4200N

Explanation:

When the submersible craft is at rest, the tension in the cable is 6000N.

With this information you can calculate the weight of the craft by summing the forces (the summation of the force is zero because the craft is at rest):

[tex]T-W=0\\\\W=T=6000N[/tex]

When the craft is going down with a constant speed, there is a drag force of 1800N. Then, by using the second Newton law you have:

[tex]T-W+F_d=0[/tex]   (1)

Fd: drag force

The summation of the forces is zero because the craft moves with constant velocity, that is, there is no acceleration.

You calculate the new tension on the cable by solving the equation (1) for T:

[tex]T=W-Fd=6000N-1800N=4200N[/tex]

hence, the tension is 4200N

After four half-lives, the amount that remains is (1/2)⁴ of the original sample.

That's (1/16) of 10 g, or 0.625 g.

It doesn't matter how long the half-life is.

A radioisotope has a starting mass of 10.0 g. Half lives of the isotopes are 0-10, 1-5, 2-2.25, 3-1.25, and 4-0.625 if the radioisotope has a half life of 2.75 years.

A chemical element in an unstable state that emits radiation as it decomposes and becomes more stable. Both the natural environment and a laboratory can produce radioisotopes. They are utilized in imaging studies and therapy in medicine.

In radioactivity, the half-life is the amount of time needed for half of a radioactive sample's atomic nuclei to spontaneously decay (convert into different nuclear species by emitting particles and energy), or, more precisely, the amount of time needed for the number of disintegrations per second.

To know more about Radioisotope, visit-

https://brainly.com/question/19472025

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Answer:

The technician must heat the frame to a temperature of T₂ = 0.0072°C

Explanation:

Change in one-dimension of an object upon heating is given by the following equation:

ΔL = α L ΔT

For the radius this equation can be re-written as follows:

ΔR = α R ΔT

where,

ΔR = Change in Radius =  2.16 cm - 2.14 cm = 0.02 cm

α = Thermal Expansion Coefficient = 1.3 x 10⁻⁴ /°C

R = Original Radius = 2.14 cm

ΔT = Change in Temperature = T₂ - 20°C

Therefore,

0.02 cm = (1.3 x 10⁻⁴ /°C)(2.14 cm)(T₂ - 20°C)

T₂ - 20°C = (0.02 cm)/(1.3 x 10⁻⁴ /°C)(2.14 cm)

T₂ = 0.0072°C + 20°C

T₂ = 20.0072°C

Answer:

The charge in each ball will be 3 * 10^-12 C

Explanation:

(Assuming the correct charge of the second ball is 8 * 10^-12)

When the balls are brought in contact, all the charges are split evenly among then.

So first we need to find the total charge combined:

(-3 * 10^-12) + (8 * 10^-12) + (4 * 10^-12) = 9 * 10^-12 C

Then, when the balls are separated, each ball will have one third of the total charge, so in the end they will have the same charge:

(9 * 10^-12) / 3 = 3 * 10^-12 C

So the charge in each ball will be 3 * 10^-12 C

Answer:

a)217m

b)222m

c)261s  

Explanation:

Considering the figure in the attachment

depth 'h'=50m

speed 'v'=0.85m/s

angle 'θ'=13°

a) we have

[tex]\frac{h}{x}[/tex]=tanθ

x = h / tanθ => 50/tan13°

x=216.57≈217m

b)we have

[tex]\frac{h}{d}[/tex]=sinθ

d=h / sinθ => 50 / sin13°

d=222.27≈222m

c)Time needed = d / v = 222/0.85

                          261.18≈261s

Answer:

The radial acceleration is  [tex]a_r = 1472667 \ m/s^2[/tex]

Explanation:

From the question we are told that

      The velocity of the red blood cell is  [tex]v_r = 470 \ m/s[/tex]

       The radial acceleration of the red blood cell is [tex]a_r = 150000g = 150000*9.8 = 1470000 \ m/s^2[/tex]

       The radius of the centrifuge is  [tex]r = 0.15 \ m[/tex]

Generally radial acceleration is  mathematically represented as

      [tex]a_r = \frac{v^2}{r}[/tex]

substituting values

     [tex]a_r = \frac{470^2}{0.15}[/tex]

     [tex]a_r = 1472667 \ m/s^2[/tex]

Explanation:

45 m/s × (3.28 ft/m) × (1 mi / 5280 ft) × (3600 s/h) = 101 mph

This is actually 3 significant figures.  To write in 2 significant figures, you must use scientific notation:

1.0×10² mph

Answer:

The ratio of the speed of light in carbon tetrachloride to the speed in ethyl alcohol is 0.93

Explanation:

The formula for the refractive index of a medium is given as:

n = c/v

where,

n = refractive index of the medium

c = speed of light in vacuum

v = speed of light in that medium

FOR CARBON TETRACHLORIDE:

n = n₁ = 1.461

v = v₁

Therefore,

1.461 = c/v₁  

v₁ = c/1.461     ----- equation (1)

FOR ETHYL ALCOHOL:

n = n₂ = 1.361

v = v₂

Therefore,

1.361 = c/v₂  

v₂ = c/1.361     ----- equation (2)

Now, dividing equation (1) by equation (2), we get:

v₁/v₂ = (c/1.461) / (c/1.361)

v₁/v₂ = 1.361/1.461

v₁/v₂ = 0.93

Hence, the ratio of the speed of light in carbon tetrachloride to the speed in ethyl alcohol is 0.93

Answer:

3859 grams

Explanation:

Given: Weight of a television = 8.50 pounds

To find: Weight of a television in grams

Solution:

1 pound = 0.454 kg and 1 kg = 1000 g

So,

1 pound = 0.454 × 1000 = 454 grams

8.50 pounds = 8.50 × 454 = 3859 grams

Therefore,

Weight of television in grams = 3859 grams

Answer:

It represents battery

Answer: I think #1 represent lights and #2 represent the battery

Answer:

I = ΔVA[1 - α (T₀ - T)]/Lρ₀

Explanation:

We have the following data:

ΔV = Battery Terminal Voltage

I = Current through wire

L = Length of wire

A = Cross-sectional area of wire

T = Temperature of wire, when connected across battery

T₀ = Reference temperature

ρ = Resistivity of wire at temperature T

ρ₀ = Resistivity of wire at reference temperature

α = Temperature Coefficient of Resistance

From OHM'S LAW we know that;

ΔV = IR

I = ΔV/R

but,  R = ρL/A   (For Wire)

Therefore,

I = ΔV/(ρL/A)

I = ΔVA/ρL

but,   ρ = ρ₀[1 + α (T₀ - T)]

Therefore,

I = ΔVA/Lρ₀[1 + α (T₀ - T)]

I = [ΔVA/Lρ₀] [1 + α (T₀ - T)]⁻¹

using Binomial Theorem:

(1 +x)⁻¹ = 1 - x + x² - x³ + ...

In case of [1 + α (T₀ - T)]⁻¹, x = α (T₀ - T).

Since, α generally has very low value. Thus, its higher powers can easily be neglected.

Therefore, using this Binomial Approximation, we can write:

[1 + α (T₀ - T)]⁻¹ = [1 - α (T₀ - T)]

Thus, the equation becomes:

I = ΔVA[1 - α (T₀ - T)]/Lρ₀

Answer:

The height will be "2.42 m".

Explanation:

The given values are:

time, t = 0.65 seconds

∴ g = 9.8

As we know,

⇒  [tex]x=vt+\frac{1}{2}gt^2[/tex]

∴ v = 0

On putting the estimated values, we get

⇒    [tex]=0+\frac{1}{2}\times 9.8\times (0.65)^2[/tex]

⇒    [tex]=\frac{1}{2}\times 9.8\times 0.4225[/tex]

⇒    [tex]=\frac{1}{2}\times 4.1405[/tex]

⇒    [tex]=2.07025 \ m[/tex]

Now,

Height, [tex]h=4.5-2.07025[/tex]

⇒             [tex]=2.42 \ m[/tex]

Answer:

Given that,  

Speed = v  

Radius = r  

We have to ascertain the precise speed  

Utilizing equation of speed  

Where, v = velocity/speed

r = radius  

= precise speed/ angular velocity

Angular Velocity :  

The precise speed is characterized by the speed of turn.  

The precise speed is straightforwardly corresponding to the direct speed and contrarily relative to the range of the molecule.  

Subsequently, The precise speed is v/r

Answer: bismuth and nitrogen, because they have the same number of valence electrons

Explanation:

Elements are distributed in groups and periods in a periodic table.

Elements that belong to same groups will show similar chemical properties because they have same number of valence electrons.

The number of valence electrons in Bismuth and nitrogen are 5 and thus thus they will show similar chemical properties and thus belong to the same group.

The atomic masses of elements in a group will differ drastically.

The group number has got nothing to be the isolation year.

Thus bismuth and nitrogen belong to same group because they have the same number of valence electrons

Answer:

D

Explanation:

i got it right in my test

Answer:

Gamma radiation

Explanation:

Electromagnetic radiations are waves that do not require material medium for their propagation, and they travel at the same velocity. When these waves are arranged with respect to increasing frequency or decreasing wavelength, it forms a spectrum.

Since Prof. Marcia Grail's device can create an electromagnetic radiation of any frequency, the appropriate radiation to achieve her goal would be gamma radiation.

Gamma radiation is a high penetrating radiation with lethal effects on exposed biological molecules, causing induction of cancer and genetic mutations even at low level.

Answer:

4.

a) W = 750 J

b) W = 2250 J

c) t = 2 sec

5. Answered in explanation

Explanation:

4.

The formula of power is given as:

P = W/t

where,

P = Power

W = Work Done

t = Time Taken

a)

Here,

P = 750 W

t = 1 sec

W = ?

Therefore,

750 W = W/1 sec

W = 750 J

b)

Here,

P = 750 W

t = 3 sec

W = ?

Therefore,

750 W = W/3 sec

W = (750 W)(3 sec)

W = 2250 J

c)

Here,

P = 750 W

t = ?

W = 1500 J

Therefore,

750 W = 1500 J/t

t = 1500 J/750 W

t = 2 sec

5.

According to Kinetic Particle Theory, the molecules are tightly packed with each other, by strong inter-molecular forces and they can only vibrate at their position. While, molecules or particles in liquids have lesser attractive forces among them. They can move in layers and can take the shape of any container. This is the reason why solid has a definite shape and liquid has none.

Answer:false

Explanation:

Answer:

d. The scale's resolution is too low to read the change in mass

Explanation:

If we want to find the change in energy of the spring, we will have to use the Hooke's Law. Hooke's Law states that:

F = kx

since,

w = Fd

dw = Fdx

integrating and using value of F, we get:

ΔE = (0.5)kx²

where,

ΔE = Energy added to spring

k = spring constant

x = displacement

The spring constant is typically in range of 4900 to 29400 N/m.

So if we take the extreme case of 29400 N/m and lets say we assume an unusually, extreme case of 1 m compression, we get the value of energy added to be:

ΔE = (0.5)(29400 N/m)(1 m)²

ΔE = 1.47 x 10⁴ J

Now, if we convert this energy to mass from Einstein's equation, we get:

ΔE = Δmc²

Δm = ΔE/c²

Δm = (1.47 x 10⁴ J)/(3 x 10⁸ m/s)²

Δm =  4.9 x 10⁻¹³ kg

As, you can see from the answer that even for the most extreme cases the value of mass associated with the additional energy is of very low magnitude.

Since, the scale only gives the mass value upto 1 decimal place.

Thus, it can not determine such a small change. So, the correct option is:

d. The scale's resolution is too low to read the change in mass

Answer:

b) there must be a component of force parallel to the motion of the object.

Explanation:

We know that work done on a body by an external force is calculated by the formula given below:

W = F.d = Fd Cos θ

where,

W = Work Done by the force on the body

F = Magnitude of force

d = displacement of the body

θ = The angle between the direction of motion of the body and the force applied

It is clear from the formula of the work done, that "F Cosθ" represents the component of the force, that is acting in the direction of motion of the object or parallel to the direction of motion of the object. So, if there is no component of force parallel to motion of object, then this factor will become zero. As a result, the work done will also be zero.

Therefore, the correct option will be:

b) there must be a component of force parallel to the motion of object.

Answer:   A    Answers. Assuming that the terminal velocity doesn't change during the fall, then the kinetic energy would remain constant. However the terminal velocity decreases during the fall since the air becomes denser at lower altitudes.

Explanation:

What happens to the KE of an object when it slows down and heats up? - Quora. The kinetic energy goes down and the loss of the kinetic energy is through the production of heat energy. In real world this is due to friction, or an opposing force that decelerates the object, or a combination of both.

Answer:

Kinetic energy stays the same

Answer:

It would cost approximately $925,455,484 million to cover continental US and Alaska with $1 bills.

Explanation:

the area of a one dollar bill = 6.5 cm x 15.5 cm = 100.75 sq cm

the approximate area of continental US + Alaska = (1,000 miles x 3,000 miles) x 1.2 = 3,600,000 sq miles

each sq mile is roughly 2.58999 sq km, so the total area in sq km = 9,323,964 sq km

1 sq km = 1,000,000 sq meters

each sq meter = 10,000 sq cm

1 sq m = 10,000 / 100.75 = 99.25558 bills

1 sq km = 99,255,583.13 bills

9,323,964 sq km = 925,455,483,900,000 bills

If the US includes the area of the Hawaii and the Alaska. It would be costing approx. $925,455,484 mn to cover continental with the $1 bills.  

Learn more about the would it cost to cover the entire land area.

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t Answer:

1) the time of the pigeon 1 is less, so it comes first

2) v = - 6,997 m / s ,  3)     v = 10.15 m / s ,

4) the displacement of the second point in greater

5)     x = 0.883 m

Explanation:

For this exercise we will use the kinematics equations

1) ask which chick reaches the ground first

we calculate for the first chick that has zero initial velocity

          y = y₀ + v₀ t - ½ g t²

          0 = yo - ½ g t²

          t = √ 2 y₀ / g

let's calculate

          t = √ (2 2.50 / 9.8)

          t = 0.714 s

We calculate the time it takes for the second chick that has velocity v = (1 i ^ - 1.5 j⁾ m / s

           y = y₀ + v₀t - ½ g t²

           0 = 2.5 - 1.5 t - ½ 9.8 t²

           4.9 t² + 1.5 t - 2.5 = 0

            t² + 0.306 t - 0.510 = 0

we solve the quadratic equation

            t = [0.306 ± √ (0.306² - 4 (-0.510))] / 2

            t = [0.306 ± 1.46] / 2

The results are

            t₁ = -0.577 s

            t₂ = 0.883 m / s

we take positive time as correct

the time of the pigeon 1 is less, so it comes first

2) the speed of the first chick is

              v = v₀ - g t

we can see that

              v = -gt

              v = - 9.8 0.714

              v = - 6,997 m / s

the negative sign indicates that the speed is down

3) the speed of the other bird is

              v = -1.5 - 9.8 0.883

               v = 10.15 m / s

4) which chick has the greatest displacement. The first point falls vertically and its displacement is y₀

The second point describes a parabola and its displacement is

           d = √ (x² + y₀²)

therefore we see that the displacement of the second point in greater

5) calculate the horizontal displacement of the second point

           x = vx t

           x = 1 0.883

           x = 0.883 m