how many continents do have in africa​

Answer:

[tex]\boxed {\boxed {\sf 40 \ kilograms}}[/tex]

Explanation:

Momentum is the product of velocity and mass. The formula is:

[tex]p=m*v[/tex]

We know the rock is falling. Its momentum is 200 kilograms meters per second and its velocity is 5 meters per second. Substitute the values into the formula.

[tex]200 \ kg \ m/s = m * 5.0 \ m/s[/tex]

We are solving for m, the mass. We must isolate the variable. It is being multiplied by 5 meters per second. The inverse of multiplication is division, so we divided both sides by 5.0 m/s.

[tex]\frac{200 \ kg \ m/s}{5.0 \ m/s}=\frac{ m* 5.0 \ m/s }{5.0 \ m/s}[/tex]

[tex]\frac{200 \ kg \ m/s}{5.0 \ m/s}=m[/tex]

The units of meters per second (m/s) cancel.

[tex]\frac{200 \ kg}{5.0 } =m[/tex]

[tex]40 \ kg = m[/tex]

The falling rock has a mass of 40 kilograms.

I can not even read this question.

What are you trying to even say?

The acceleration of the car with two (2) washers added is equal to 0.33 [tex]m/s^2[/tex].

Given the following data:

An acceleration can be defined as the rate of change of velocity of an object with respect to time and it is measured in meter per seconds square.

In Science, the average acceleration of an object is calculated by subtracting its initial velocity from the final velocity and dividing by the change in time for the given interval.

Mathematically, average acceleration is given by this formula:

[tex]a = \frac{V\;-\;U}{t_f-t_i}[/tex]

Where:  

Substituting the given parameters into the formula, we have;

[tex]a = \frac{0.36\;-\;0.13}{2.61\;-\;1.92}\\\\a=\frac{0.23}{0.69}[/tex]

a = 0.33 [tex]m/s^2[/tex]

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Answer:

[tex]d=1.2m[/tex]

Explanation:

From the question we are told that:

Spring constant [tex]k= 4000 N/m[/tex]

Compressed [tex]l_d= 10cm=>0.10[/tex]

Mass [tex]m=1.0kg[/tex]

Length of horizontal section  [tex]l=5.0-m[/tex]

Coefficient of friction [tex]\mu=0.20[/tex]

Angle [tex]\theta=60 \textdegree[/tex]

Generally the equation for Kinetic Energy K.E is mathematically given by

 [tex]K.E=\mu mgL+mgdsin\theta[/tex]

 [tex]\frac{1}{2}k*l_d^2=\mu mgL+mgdsin\theta[/tex]

 [tex]\frac{1}{2}(4000)*0.1^2=0.2*1*9.8*5+1*9.8*d*sin60[/tex]

 [tex]d=1.2m[/tex]

Answer:

Capacitance= 1.18×10^-6

Answer: 1.18*10^-6

Explanation:

Answer:

speeding up is the answer

Explanation:

from the graph it can be seen that as the time (horizontal axis) increases the speed of vehicle (vertical axis) increases

Answer: The energy released as thermal energy is 6.5 J

Explanation:

Energy stored by the spider when it relaxes is given by:

[tex]E_o=\text{Resilience}\times \text{Work}[/tex]

We are given:

Resilience = 0.35

Work done = 10.0 J

Putting values in above equation, we get:

[tex]E_o=0.35\times 10\\\\E_o=3.5J[/tex]

Energy released at thermal energy is the difference between the work done and the energy it takes to relaxes, which is given by the equation:

[tex]E_T=\text{Work done}-E_o[/tex]

Putting values in above equation, we get:

[tex]E_T=(10-3.5)=6.5J[/tex]

Hence, the energy released as thermal energy is 6.5 J

The energy released as thermal energy when 10 J of work is done to stretch silk will be 6.5 J

Thermal energy refers to the energy contained within a system that is responsible for its temperature. Heat is the flow of thermal energy.

Energy stored by the spider when it relaxes is given by:

[tex]\rm E_o=Resilience \ \times Work[/tex]

We are given:

Resilience = 0.35

Work done = 10.0 J

Putting values in above equation, we get:

[tex]\rm E_o=0.35\times 10[/tex]

[tex]E_o=3.5\ J[/tex]

Energy released at thermal energy is the difference between the work done and the energy it takes to relaxes, which is given by the equation:

[tex]E_T=\rm Work done -E_o[/tex]

Putting values in above equation, we get:

[tex]E_T=(10-3.5)=6.5\ J[/tex]

Hence, the energy released as thermal energy is 6.5 J

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Answer:

171.5 m

Explanation:

To find the distance, speed x time

342 x 0.5

171.5 m

Hope this helped!

Answer:

0.3333

Explanation:

Acceleration = change in velocity/time

a = 20 m/s / 60 m/s

a = 0.3333 m/s^2

Answer:

25

Explanation:

magnitude and (b) direction (as an angle relative to the x axis) of the velocity

Answer:

5

Explanation:

Answer:

The answer is below

Explanation:

The length of the rope is equal to the radius of the circle formed by the complete rotation of the rope. Therefore the radius = 1.50 m.

a) The distance covered by the rope when completing one rotation is the same as the perimeter of the circle. Hence:

Distance covered in one rotation = 2π * radius = 2π * 1.5 = 3π meters

The velocity of the ball = Distance / time = 3π meters / 3.4 seconds = 2.77  m/s

b) The initial velocity (u) is 0 m/s, the final velocity is 2.77 m/s during time (t) = 3.4 s. Hence acceleration (a):

v = u + at

2.77 = 3.4a

a = 0.82 m/s²

c) Force on ball = mass * acceleration = 4 * 0.82 = 3.28 N

Answer:

the correct statement is 2. The solid plate will have the greater angular acceleration.

the correct phrase is 4. The plate with the hole has its mass distributed further out from the axis of rotation, which will increase its moment of inertia.

Explanation:

Newton's second law expression for rotational motion is

         τ = I α         (1)

where the torque is

         τ = F r

in this case, as the discs have the same radius and the applied force is the same, the torque is the same on the two discs.

The moment of inertia is given by the expression

        I =∫ r² dm

for bodies with high symmetry are tabulated

the moment of inertia for in disk solid is     I₁ = ½ m R₂²

the moment for a disk with a hole               I₂ = ½ m (R₁² + R₂²)

We can see that the moment of inertia of the disk with the hole is greater than the moment of inertia of the solid disk.

Let's use equation 1

          α = τ/I

therefore the angular acceleration is lower for the body with the higher moment of inertia, consequently the solid disk has higher angular acceleration

the correct statement is 2

The reason is because the moment of inertia is higher for the hollow disk.

the correct phrase is 4

Answer:

[tex]R _{t} = R _{0}( \alpha t + 1) \\ = 4 \times {10}^{ - 3} (3.9 \times {10}^{ - 3} \times 20 + 1) \\ = 4 \times {10}^{ - 3} (1.078) \\ = 4.312 \times {10}^{ - 3} \: Ω[/tex]

Answer:

The beam of electrons would be flattened into a oval that is long in the x-axis and short in the y-axis.

Explanation:

A beam of moving electrons enters the quadrupole, with velocity parallel to the charged rods. When the beam enters the device, its cross-sectional profile is circular. On the other side, the beam of electrons would be flattened into a oval that is long in the x-axis and short in the y-axis.

The directions is shown in figure.

Answer:

by the drag force, 2.4004512 × 10⁻⁵ J is added to the air.

Explanation:

Given the data in the question;

drag coefficient of Cd = 1.4

speed v = 6.0 m/s

One model expands to a square 1.8 mm on a side

Area A = 1.8 × 1.8 = 3.24 mm² = 3.24 × 10⁻⁶ m²

distance travelled s = 240 mm = 0.24 m

we know that; density of air e = 1.225 kg/m³

Now,

Dragging force F[tex]_D[/tex] = ( Cd × e × v² × A  ) / 2

thermal energy = F[tex]_D[/tex] × s

so

thermal energy = ( 1.4 × 1.225  × (6)² × (3.24 × 10⁻⁶) × 0.24  ) / 2

thermal energy = ( 4.8009024 × 10⁻⁵ ) / 2

thermal energy = 2.4004512 × 10⁻⁵ J

Therefore,  by the drag force, 2.4004512 × 10⁻⁵ J is added to the air.

Answer:

Magnitude = 15.86 units

direction = 69 degree below negative X axis

Explanation:

A = 20 units at 60.0° counterclockwise from the negative x - axis

B = 40 units at 30.0° counterclockwise from the positive x - axis

C = 35 units at 60.0° clockwise from the negative y - axis

Write the vectors in the vector form

[tex]\overrightarrow{A} =20 (- cos 60 \widehat{i} - sin 60 \widehat{j})=- 10\widehat{i} - 17.3 \widehat{j}\\\\\overrightarrow{B} =40 (cos 30 \widehat{i} + sin 30 \widehat{j})= 34.6\widehat{i} +20 \widehat{j}\\\\\overrightarrow{C} =35 (- sin 60 \widehat{i} - cos 60 \widehat{j})=- 30.3\widehat{i} - 17.5 \widehat{j}\\\\Now\\\\overrightarrow{A} + \overrightarrow{B} + \overrightarrow{C} = (- 10 + 34.6 - 30.3) \widehat{i} + (-17.3 + 20-17.5)\widehat{j}\\\\[/tex]

[tex]\\\overrightarrow{A} + \overrightarrow{B} + \overrightarrow{C} = - 5.7\widehat{i} -14.8\widehat{j}[/tex]

The magnitude is given by

[tex]= \sqrt{5.7^2 + 14.8^2} = 15.86 units[/tex]

The direction is given by

[tex]tan\theta = \frac{- 14.8}{- 5.7}\\\\\theta= 69^o[/tex]

below negative X axis.  

Answer:

3.92N

Explanation:

Force= mass×accelerarion due gravity

But mass= 0.40kg

acceleration due to gravity = 9.8 m/s^2

Force = 0.40×9.8

Force=3.92N

Answer:

- increasing use of hybrid crops

- altering genes in DNA to create new plants

- developing disease or pest resistant crops

Explanation:

The use of genetic factors to influence the growth of a plant encompasses manipulating the genetic constituent (gene) of such plant.

For example,

- Increasing use of hybrid crops entails mating two pure bred plants based on a gene of interest responsible for a particular trait, to form a hybrid.

- Altering genes in DNA to create new plants is also a genetic factor as it has to with gene modification.

- developing disease or pest resistant crops means that the genetic make up of such plant has been modified to be resistant to pest/disease.

Answer:

(A - B).A = -2.91

Explanation:

First, let's define the sum and dot product of vectors.

For two vectors V = (x₁, y₁) and W = (x₂, y₂) we have:

sum (or subtraction):

V + W = (x₁, y₁) +  (x₂, y₂)  = (x₁ + x₂, y₁ + y₂)

dot product:

V.W =  (x₁, y₁).(x₂, y₂) = x₁*x₂ + y₁*y₂

Here remember the notation:

V = x₁*i + y₁*j =  (x₁, y₁)

Now let's solve our problem, we have:

A = (3.7, 1.0)

B = (3.0, 6.5)

Then:

(A - B).A = (  (3.7, 1.0) -  (3.0, 6.5) ).(3.7, 1.0)

              = (3.7 - 3.0, 1.0 - 6.5).(3.7, 1.0)

              = (0.7, -5.5).(3.7, 1.0) = (0.7*3.7) + (-5.5)*(1.0) = -2.91

Answer:

Explanation:

a)

Given that:

V = 25 mi/hr

To ft/sec, we have:

[tex]V = 25 \times \dfrac{5280}{3600} ft/s[/tex]

[tex]V = \dfrac{110}{3} ft/s[/tex]

[tex]\rho = 0.075 \ lb/ft^3[/tex]

[tex]\rho = 0.075 \times \dfrac{1 \ lbf s^2/ft}{32.174 \ lbm}[/tex]

[tex]\rho = \dfrac{0.075}{32.174 } lbf.s^2/ft^4[/tex]

[tex]C_d = 0.28[/tex]

A = 25ft²

Recall that:

The drag force [tex]F_d =\dfrac{C_dA \rho V^2}{2}[/tex]

[tex]F_d =\dfrac{1}{2}\times 0.28 \times 25\times \dfrac{0.075}{32.174}\times (\dfrac{110}{3})^2[/tex]

[tex]F_d =10.967 \ lbf[/tex]

[tex]P = F_dV \\ \\ P = 10.97 \times (\dfrac{110}{3}} \\ \\ P = 402.3 \ hp[/tex]

For 70 miles per hour, we have:

[tex]V = 70 \times \dfrac{5280}{3600} ft/s[/tex]

[tex]V = \dfrac{308}{3} ft/s[/tex]

The drag force [tex]F_d =\dfrac{C_dA \rho V^2}{2}[/tex]

[tex]F_d =\dfrac{1}{2}\times 0.28 \times 25\times \dfrac{0.075}{32.174}\times (\dfrac{308}{3})^2[/tex]

[tex]F_d =85.99 \ lbf[/tex]

[tex]P = F_dV \\ \\ P = 85.99 \times (\dfrac{308}{3}}) \\ \\ P = 8828.2 \ hp[/tex]

Answer:

B. The Spring equinox

Explanation:

The vernal equinox marks the moment the sun crosses the celestial equator.  The vernal equinox happens on March 19, 20, or 21 every year in the Northern Hemisphere. In the Southern Hemisphere, this same event marks the beginning of fall.  (Source: What Exactly Is The Spring Equinox? - Dictionary.com)

Hopefully this helps.

Answer:

a) S =  63.2 km/h

b) V =  63.2 km/h*(-0.316 , 0.949)

Explanation:

Let's define:

North as the positive y-axis

East as the positive x-axis.

Also, remember the relation:

Distance = Time*Speed

Let's assume that she starts at the position (0km, 0km)

Then she travels due North at 90km/h for two hours, then the displacement is

90km/h*2h = 180km to the north

Then the new position is:

(0km, 180km)

Then she travels West at 60km/h for one hour.

Then the distance traveled to the West (negative x-axis) is:

60km/h*1h = 60km to the west

Then the new position is:

(-60km, 180km).

a) The average speed is defined as the quotient between the displacement and the time.

We know that the total time traveled is 3 hours.

And the displacement is the difference between the final position and the initial position.

this is:

D = √( -60km - 0km)^2 + (180km - 0km)^2)=

D = √( (60km)^2 + (180km)^2) = 189.7 km

Then the average speed is:

S = (189.7 km)/(3 h) = 63.2 km/h

b) Now we want to find the average velocity, this will be equal to the average speed times a versor that points from the origin to the direction of the final position.

So, if the final position is (-60km, 180km)

We need to find a vector that represents the same angle, but that is on the unit circle.

Then, if the module of the final position is 189.7 km (as we found above), then the versor is just given by:

(-60km/ 189.7 km, 180km/ 189.7 km)

(-60/189.7 , 180/189.7)

We can just check that the module of the above versor is 1.

[tex]module = \sqrt{(\frac{-60}{189.7} )^2 + (\frac{180}{189.7} )^2} = \frac{1}{189.7}* \sqrt{(-60 )^2 + (180 )^2} = 1[/tex]

Then the average velocity is:

V = 63.2 km/h*(-60/189.7 , 180/189.7)

We can simplify our versor so the velocity equation is easier to read:

V = 63.2 km/h*(-0.316 , 0.949)

Its angular momentum of a satellite will drop even as satellite panel stretch because of the reduction in angular velocity brought on by the drag effect.

A portion of the star's mass is blown off during the supernovae that come before the creation of black holes, taking some of the star's total angular momentum with it.The leftover material sinks into the star's core while continuing to spin rapidly.

Magnus effect: When there is relative movement between both the spinning item and the fluid, a sideways force is generated on a rotating cylindrical or spherical object immersed in the fluid (liquid or gas).In honor of the German chemist and physicist H.G.

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Answer:

C

Explanation:

100%

Answer:

3.83×10¯⁴ N

Explanation:

From the question given above, the following data were obtained:

Charge 1 (q₁) = +2.4x10¯⁸ C

Charge 2 (q₂) = +1.8x10¯⁶ C

Distance apart (r) = 1.008 m

Electrical constant (K) = 9×10⁹ Nm²/C²

Force (F) =?

The magnitude of the electrical force acting between the two charges can be obtained as follow:

F = Kq₁q₂ / r²

F = 9×10⁹ × 2.4x10¯⁸ × 1.8x10¯⁶ / (1.008)²

F = 0.0003888 / 1.016064

F = 3.83×10¯⁴ N

Thus the magnitude of the electrical force acting between the two charges is 3.83×10¯⁴ N

Answer:

the mass of the box is 17 kg

Explanation:

Given;

magnitude of the force applied by the fisherman, F = 51 N

magnitude of acceleration of the box, a = 3 m/s²

the mass of the box is calculated using Newton's law of motion;

F = ma

where;

m is the mass of the box

m = F / a

m = (51) / (3)

m = 17 kg

Therefore, the mass of the box is 17 kg

Answer:

3.73 * 10^16   photons/sec

Explanation:

power supply = 3.0 V

Emits 440 nm blue light

current in LED = 11 mA

efficiency of LED = 51%

Calculate the number of photons per second the LED will emit

first step : calculate the energy of the Photon

E = hc / λ

   =(  6.62 * 10^-34 * 3 * 10^8 )  / 440 * 10^-9

   = 0.0451 * 10^-17  J

Next :

Number of Photon =( power supply * efficiency * current ) / energy of photon

= ( 3 * 0.51 * 11 * 10^-3 ) / 0.0451 * 10^-17

= 3.73 * 10^16 photons/sec

Answer:

[tex]\triangle P=1.95*10^{-4}[/tex]

Explanation:

Mass [tex]m=0.001[/tex]

Diameter [tex]d=1.2m[/tex]

Length [tex]l=10m[/tex]

Generally the equation for Volume flow rate is mathematically given by

 [tex]Q=AV[/tex]

 [tex]V=\frac{Q}{\pi/4D^2}[/tex]

 [tex]V=\frac{0.001}{\pi/4(1.2)^2}[/tex]

 [tex]V=8.84*10^{-4}[/tex]

Generally the equation for Friction factor is mathematically given by

 [tex]F=\frac{64}{Re}[/tex]

Where Re

Re=Reynolds Number

 [tex]Re=\frac{pVD}{\mu}[/tex]

 [tex]Re=\frac{1000*8.84*10^{-4}*1.2}{1.002*10^{-3}}[/tex]

 [tex]Re=1040[/tex]

Therefore

 [tex]F=\frac{64}{Re}[/tex]

 [tex]F=\frac{64}{1040}[/tex]

 [tex]F=0.06[/tex]

Generally the equation for Friction factor is mathematically given by

 [tex]Head loss=\frac{fLv^2}{2dg}[/tex]

 [tex]H=\frac{0.06*10*(8.9*10^-4)^2}{2*1.2*9.81}[/tex]

 [tex]H=19.9*10^{-9}[/tex]

Where

[tex]H=\frac{\triangle P}{\rho g}[/tex]

[tex]\triangle P=\frac{19.9*10^{-9}}{10^3*(9.81)}[/tex]

[tex]\triangle P=H*\rho g[/tex]

[tex]\triangle P=1.95*10^{-4}[/tex]

Answer:

29.4 J

Explanation:

Before the drop, the system has only the gravitational potential energy, and this energy us given by mass×gravity×height:

1.5•9.8•2 = 29.4 J

Answer:

The correct answer will be "0.25 sec".

Explanation:

The graph of the given question is attached below.

According to the graph of the question,

Time,

T = 1 sec

For the upward velocity,

⇒ [tex]t = \frac{T}{4}[/tex]

By putting the value, we get

⇒    [tex]=\frac{1}{4}[/tex]

⇒    [tex]=0.25 \ sec[/tex]