What is the energy of the 30 kg skateboarder at 2 m off the ground traveling at 3 m/s?

Answers

Answer 1
1) The kinetic energy of an object is given by:

where m is the object's mass and v its speed.

By using this equation, we find the initial kinetic energy of the skateboarder:

and the final kinetic energy as well:


So, her change in kinetic energy is


2) The work-energy theorem states that the work done to increase the speed of an object is equal to the variation of kinetic energy of the object:

Therefore, the work done by the skateboarder is

Related Questions

The water droplets appear to be causing patterns of black and bright blue fringes. in terms of water in the real world (in a bowl, sink or pond), what do the bright blue and black colors mean?

Answers

Answer:

The bright blue and black colors represent the following:

Constructive and destructive interference are represented by the blue and black colors, respectively. When two water waves collide constructively, the resultant wave is bright blue, while when they collide destructively, the resultant wave is black in color.

Explanation:

   When two propagating waves with the same frequency (say, [tex]\nu[/tex]) and wavelength (say,[tex]\lambda[/tex]) but slightly different amplitudes (say, A 1 and A 2) traveling in the same direction interfere or are superimposed on each other (that is incident at the same point or object), a third resultant wave with a different amplitude (increased or decreased) but same wavelength and frequency is generated.  

The direction difference between the two waves determines whether they intervene constructively (increasing the amplitude of the resultant wave) or destructively (increasing the amplitude of the resultant wave) (decreased amplitude of the resultant wave). To put it another way, when the difference in direction between the two waves is of the form -

      [tex]\Delta x = n\lambda , n=0,1,2,.....[/tex] is the order of interference.

The two waves are then assumed to be in phase, and the interference is constructive, resulting in the resultant wave having a larger amplitude (which is the sum of the two amplitudes [tex]A_1 +A_2[/tex]  also known as a maxima). When the difference in direction between the two waves is in the form -

  [tex]\Delta x = (2n-1)\frac{\lambda}{2} , n=0,1,2,.....[/tex] is the order of interference.

The two intervening waves are then said to be out of phase, and the interference is disruptive, resulting in the resultant wave having a lower amplitude (which is the difference between the two amplitudes [tex]A_1+A_2[/tex], also known as a minima).

Hence , the graphical representation of constructive (blue )and destructive (black) is attached.

Where does the pendulum have 100 J of potential energy?

Answers

Answer:

Potential energy is related to mass and height. More context is required otherwise the answer here is an equation with several unknowns. PE = mgL(1 – COS θ) where θ is the angle away from the vertical and L is the length of the string.

Explanation:

Light travels at a speed of 3.0 ´ 108 m/s. If it takes light from the sun 5.0 ´ 102 s to reach Earth, what is the distance between Earth and the sun?

Answers

Answer:

The distance between the Earth and the Sun is:

1.5 multiplied by 10 raised to the power 8 km

Explanation:

(5.0 x 10²) x (3.0 x 10⁸) = 1.5 x 10¹¹ meters = 1.5 x 10⁸ km.

Please help me with 17 and 18!!!!!! (It's related to 16) It's due today!!!!! NO LINK PLEASE!!!!!!!!

Answers

Answer:17: A wave can be defined as follows: It is important to realize that a wave is quite a different object than a particle. A baseball thrown though a window transfers energy from one point to another, but this involves the movement of a material object between two points.

Explanation:

18: In this way, we classify waves into electromagnetic and mechanical waves. The main difference between mechanical and electromagnetic waves is that electromagnetic waves do not require a medium to propagate whereas mechanical waves require a medium in order to propagate.

If there is a ball sitting on top of a hill with 100J of GPE. How much KE should there be at the bottom of the hill if there is no friction?

Answers

GPE=mgh=100J
KE=1/2mv^2
Assume there would be no more potential energy,
GPE=KE
100J due to energy conservation law

Fill in the blanks with suitable pronouns.
1. Baby bird learns to fly
2. The two line intersect _______ at the middle position.
3. ______ had the courage to stand against the unjust treatment to the poor.
4. _______ is on the line?
5. smitha works in a gym ____ is my trainer​

Answers

1)Baby bird cannot fly. Their mother has to feed \bf\underline{them}them

2. Vijay likes riding my bicycle. I sometimes lend \bf\underline{it}it to \bf\underline{him}him

3. Sooraj and I are brothers. \bf\underline{we\:both}weboth share the same bedroom.

4. Ravina isn't well. Dad is taking to the doctor. (No personal pronouns required)

5. My sister is a teacher. \bf\underline{She}She teaches Maths.

Charge is given in microcoulombs. What must you multiply the charge by to use Coulomb's
law to calculate the electric force?
O
A. 10-6
O
B. 10-3
C. 106
D. 103

NEED ANSWER NOW
NO LINK

Answers

Answer:

Option A. 10¯⁶

Explanation:

To know which option is correct, we must bear in mind, the relationship between micro coulomb (μC) and coulomb (C). This is given below:

Recall:

1 μC = 10¯⁶ C

Therefore, to convert micro coulomb (μC) to coulomb (C), multiply the value given in micro coulomb (μC) by 10¯⁶.

Thus, option A gives the correct answer to the question.

What's an conductor?

A.material that electric current passes easily through
B.material that doesn't conduct electrical current
C.Other:

Answers

Answer:

A. Material that electric current passes easily through.

Explanation:

What happened to the kelp forest when the otter was hunted to near extinction?

Answers

Answer: Sea otter is the pioneer species in the kelp forest as it regulates and controls the population of other species in the kelp forest.

Explanation:

If sea otters are hunted and their population is brought to extinction then this will cause major harm the ecosystem of the kelp forest and it will disturb the ecological balance in the kelp forest. The herbivorous animals consumed by the sea otters will increase in population and they will consume a lot of vegetation in the forest. The kelp forest which forms the coastline will not remain effective in providing protection against the storms to the neighboring areas.

this is not a question its a thanks zerofrancisco

Answers

Answer:

⠀⠀⠀⠀⠀

Explanation:

Answer:

the guy above me has great humor

Explanation:

An electromagnetic wave with frequency 65.0Hz travels in an insulating magnetic material that has dielectric constant 3.64 and relative permeability 5.18 at this frequency. The electric field has amplitude 7.20×10−3V/m. What is the wavelength of the wave?

Answers

Answer:

  The wavelength of the wave is [tex]1.06\times10^6 m[/tex]  

Explanation:

Lets calculate

We know an electromagnetic wave is propagating through an insulating magnetic material of dielectric constant K and relative permeability [tex]K_m[/tex] ,then the speed of the wave in this dielectric medium is [tex]\nu[/tex] is less than the speed of the light c and is given by a relation

               [tex]\nu=\frac{c}{\sqrt{KK_m} }[/tex]  --------- 1

In case the electromagnetic  wave propagating through the insulating magnetic material , the amplitudes of electric and  magnetic fields are related as -

             [tex]E_m_a_x= \nu B_m_a_x[/tex]

The magnitude of the 'time averaged value' of the pointing vector is called the intensity of the wave and is given by a relation

                       [tex]I = S_a_v[/tex]

                        [tex]\frac{E_m_a_xB_m_a_x}{2K_m\mu0}[/tex]----------- 3

now , we will find the speed of the propagation of an electromagnetic wave by using equation 1

[tex]\nu=\frac{c}{\sqrt{KK_m} }[/tex]

Putting the values ,

   =[tex]\nu= \frac{3.00\times10^8}{\sqrt{(3.64)(5.18)} }[/tex]

 =[tex]0.6908\times10^8m/s[/tex]

 = [tex]6.91\times10^7m/s[/tex]

Now , using this above solution , we will find the wavelength of the wave -

     [tex]\lambda=\frac{\nu}{f}[/tex]

    Putting the values from above equations -

  [tex]\frac{6.91\times10^7m/s}{65.0Hz}[/tex]

        [tex]\lambda= 1.06\times10^6 m[/tex]

Hence , the answer is [tex]\lambda= 1.06\times10^6 m[/tex]

bit.♠ly/3♠vhMu♠vJ remove symbols before searching or it wont work, there was a bug stoping me from attaching the image so there it is

Answers

Answer:

k and...

Explanation:

Answer:

no thank you.

explanation: Do not want to

26. A solid wheel accelerates at 3.25 rad/s2 when a
force of 4.5 N exerts a torque on it. If the wheel
is replaced by a wheel which has all of its mass
on the rim, the moment of inertia is given by
1 = mr? What force should be exerted on the
strap to give the same angular velocity?

Answers

Answer:

9.0 N

Explanation:

The location of the mass of the wheel on the wheel = Evenly distributed

The acceleration of the solid wheel, α = 3.25 rad/s²

The applied force on the wheel = 4.5 N

The location mass of the replacement wheel = All on (around) the rim

The moment of inertia of the new wheel, I = m·r² (From an online source)

We have;

The moment of inertia for a solid wheel = 1/2·m·r²

The torque, τ = Moment of inertia, I × Acceleration, α

For the solid wheel, we have;

τ  = 1/2·m·r² × 3.25 rad/s²

τ = r × F = r × m × a

For the replacement wheel, we have;

τ  = m·r² × 3.25 rad/s² = 2 × 1/2·m·r² × 3.25 rad/s²

∴ τ = 2 × r × F

Given that the radius remains the same, the force applied on the replacement wheel needs to be doubled

The force that should be exerted on the strap to give the same angular velocity, F' = 2 × F

The required force, F' = 2 × 4.5 N = 9.0 N.

Which is a property of every
mixture?

Answers

One substance can be separated from another through physical means is a property of every mixture.

A 5000kg elephant steps into a large spring and compresses it from 1m long to 50cm long what is the spring constant of the spring

Answers

Answer: 98 kN/m

Explanation:

Given

Mass of elephant [tex]m=5000\ kg[/tex]

Spring compresses from [tex]1\ m\ (100\ cm) \text{to}\ 50\ cm[/tex]

i.e. change in length is [tex]100-50=50\ cm[/tex]

spring force is given by  [tex]kx[/tex]

where k=spring constant

x=change in length

The weight of elephant must be equal to the spring force

[tex]\Rightarrow W=kx\\\Rightarrow 5000\times 9.8=k\times 0.5\\\Rightarrow k=98,000\ N/m\ or\ 98\ kN/m[/tex]

PLEEEEASE HELP ME PLEASE WILL GIVE BRAINLIEST

Answers

C. 7.8 hz I think! Hope this helped ☺️

If the harmonic is 66 Hz, find the fundamental frequency

Answers

Pretty sure it’s 11hz

Which best describes the energy of a sound wave as it travels through a medium?
It increases.
lt decreases.
It remains the sam.
It depends on the medium,

Answers

Answer:

it depends on the medium :D

Plz Helpp

A vehicle has a Kinetic Energy of 75000 J and is moving at a velocity of 5 m/s. What is the mass of the vehicle?​

Answers

300

could i get brainiest

If an object possesses 500 J of potential energy, how much work is needed to lift this object?


a) 500 J

b) 250 J

c) 150 J

d) 1000 J

Answers

Answer:

a) 500 J

Explanation:

Potential energy can be defined as an energy possessed by an object or body due to its position.

Mathematically, potential energy is given by the formula;

[tex] P.E = mgh[/tex]

Where,

P.E represents potential energy measured in Joules.

m represents the mass of an object.

g represents acceleration due to gravity measured in meters per seconds square.

h represents the height measured in meters.

In Science, the potential energy possessed by an object or body is the same as the work done by the object or body.

Since we know that the object possessed 500 Joules of potential energy; it would ultimately require to do a work of 500 Joules to lift the object.

Mathematically, work done = force * distance

But force = mass * acceleration due to gravity

F = mg; d = h

Substituting into the work done formula, we have;

Hence, Workdone = Fd = mgh

If the current of a circuit is 1.5 A, and the power is 24 W. what is the resistor?

Answers

Answer:

The resistor has a resistance of 10.667 ohms.

Explanation:

By Ohm's Law, voltage ([tex]V[/tex]), in volts, is directly proportional to the current ([tex]i[/tex]), in amperes, and by definition of power ([tex]\dot W[/tex]), in watts, we have the following formula:

[tex]\dot W = i^{2}\cdot R[/tex] (1)

Where [tex]R[/tex] is the resistance, in ohms.

If we know that [tex]\dot W = 24\,W[/tex] and [tex]i = 1.5\,A[/tex], then the resistance of the resistor is:

[tex]R = \frac{\dot W}{i^{2}}[/tex]

[tex]R = 10.667\,\Omega[/tex]

The resistor has a resistance of 10.667 ohms.

it took 500 n of force to push a car 4 meters. how much work was done?

Answers

Answer:

2000J

Explanation:

The formula for work is W=Force x Distance

W=FxD

W=500N x 4m

W=2,000 Joules

Divers get "the bends" if they come up too fast because gas in their blood expands, forming
bubbles in their blood. If a diver has 0.05 L of gas in his blood under a pressure of 25,000
kPa, then rises to a depth where his blood has a pressure of 5000 kPa, what will be the
volume in liters of gas in his blood?

Answers

Answer:

V= 0.25L

Explanation:

skier accelerates down the hill at a speed of 18 and reaches the bottom of the hill at a speed of 36 in 6 seconds
What an acceleration of the skier​

Answers

Answer:

3 m/s²

Explanation:

Initial Velocity, u = 18

Final velocity, v = 36

Time, t = 6 seconds

Acceleration is the change in velocity of a body with time. It obtained using the relation :

Acceleration = (v - u) / t

Acceleration = (36 - 18) / 6

Acceleration = 18 / 6

Acceleration = 3m/s²

Hence, acceleration of the skier is 3m/s²

Calculate the potential energy of a rock with a mass of 55 kg as it sits on a cliff that is 27 m high

Answers

Answer:

The potential energy is zero since the rock isn't moving.

What is meant by uniform motion ? Write with an example.

Answers

Answer:

This type of motion is defined as the motion of an object in which the object travels in a straight line and its velocity remains constant along that line as it covers equal distances in equal intervals of time, irrespective of the duration of the time.

Explanation:

In Physics, uniform motion is defined as the motion, wherein the velocity of the body travelling in a straight line remains the same. When the distance travelled by a moving thing, is same at several time intervals, regardless of the time length, the motion is said to be uniform motion.

Which of the following correctly defines the speed of a wave?
O A. v=1
B. A = vf
O C. v= f 2
OD. =v2

Answers

The correct answer is B I think

Answer:

V = f x λ

Explanation:

The options are confusing

Two identical charged pith balls are brought together to touch each other. They are then
allowed to move freely. The charge on pith ball A is –30 nC and on pith ball B is – 5 nC.
What is the charge on each after they separate?

Answers

Answer:

-17.5 nC

Explanation:

charge A = -30 nC

charge B = -5 nC

After adding them it would be the average of the two charges because of the getting same voltage difference. so

c = (-30+(-5)) / 2 nC

c= -17.5 nC

answer is -17.5 nC

A transverse wave vibrates its medium __________ to the forward motion of the wave, and a longitudinal wave vibrates its medium __________ to the forward motion of the wave.

perpendicular; circularly

parallel; circularly

parallel; perpendicular

perpendicular; parallel

Answers

Answer:

Perpendicular ; Parallel

1.45 L of 16°C water is placed in a refrigerator. The refrigerator's motor must supply an extra 10.7 W power to chill the water to 6°C in 0.7 hr. What is the refrigerator's coefficient of performance?

Answers

Answer:

The coefficient of performance of the refrigerator is 2.251.

Explanation:

In this case, the coefficient of performance of the refrigerator ([tex]COP[/tex]), no unit, is equal to the ratio of the heat rate received from the water to the power needed to work, that is:

[tex]COP = \frac{\dot Q_{L}}{\dot W}[/tex] (1)

[tex]COP = \frac{\rho\cdot V\cdot c_{w}\cdot \Delta T}{\dot W \cdot \Delta t}[/tex] (2)

Where:

[tex]\dot Q_{L}[/tex] - Heat rate received from the water, in watts.

[tex]\dot W[/tex] - Power, in watts.

[tex]\rho[/tex] - Density of water, in kilograms per cubic meter.

[tex]V[/tex] - Volume of water, in cubic meters.

[tex]c_{w}[/tex] - Specific heat of water, in joules per kilogram-degree Celsius.

[tex]\Delta T[/tex] - Temperature change, in degrees Celsius.

[tex]\Delta t[/tex] - Cooling time, in seconds.

If we know that [tex]\rho = 1000\,\frac{kg}{m^{3}}[/tex], [tex]V = 1.45\times 10^{-3}\,m^{3}[/tex], [tex]c_{w} = 4187\,\frac{J}{kg\cdot ^{ \circ}C}[/tex], [tex]\Delta T = 10\,^{\circ}C[/tex], [tex]\dot W = 10.7\,W[/tex] and [tex]\Delta t = 2520\,s[/tex], then the coefficient of refrigeration of the refrigerator is:

[tex]COP = \frac{\rho\cdot V\cdot c_{w}\cdot \Delta T}{\dot W \cdot \Delta t}[/tex]

[tex]COP = 2.251[/tex]

The coefficient of performance of the refrigerator is 2.251.

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