A 70 kg man is running up the stairs which is 3m high in 2s.(a)How much work is done by the man?(b)What is the power exerted by the man? (Use g = 10ms 2)​

Answers

Answer 1

Explanation:

m = 70 kg

s = 3m

t =2s

g = 10 m/s²

(a)How much work is done by the man?

W = Fs

= mg X s

= 70 x 3 x 10

= 210 x 10

= 2100 Joule

(b)What is the power exerted by the man?

P = W/t

= 2100/2

P = 1050 Watt


Related Questions

The amplitude of a lightly damped oscillator decreases by 4.2% during each cycle. What percentage of the mechanical energy of the oscillator is lost in each cycle?

Answers

Answer:

V= A ω      maximum KE of object in SHM

V2 / V1 = .958     ratio of amplitudes since ω is constant

KE2 / KE1 = 1/2 m V2^2 / (1/2 m V1^2) = (V2 / V1)^2

KE2 / KE1 = .958^2 = .918

So KE2 = .918 KE1 and .082 = 8.2% of the energy is lost in one cycle

Two moles of an ideal monatomic gas go through the cycle abc. For the complete cycle, 800 J of heat flows out of the gas. Process ab is at constant pressure, and process bc is at constant volume. States a and b have temperatures Ta = 200 K and Tb = 300 K.
(a) Sketch the all possible pV-diagrarns for the cycle.
(b) What is the work W for the process ca?

Answers

a) Sketches of all possible pv-diagrams for the cycle are attached below

b) The work W[tex]_{ac}[/tex] for the process Ca is : 2462.8  J

Given data :

Amount of heat flowing out = 800 J

Ta = 200 K

Tb = 300 K

R = 800

B) Determine the work W for the process Ca

Wₐs = -pdv

       = - [ pVb - pVa ] ---- ( 1 )

note : pVb = nRTb ,  pVa = nRTa

Equation ( 1 ) becomes

= -nR [ Tb - Ta ]

= - 2(8.314 ) [ 300 - 200 ]

= - 1662.87

given that W[tex]_{bs}[/tex] = 0 which is isochonic

dv = 0 ( cyclic process ) = d∅ - dw

∴ 0 = 800 - ( Wₐs  +  W[tex]_{ac}[/tex] )

Therefore : W[tex]_{ac}[/tex] = 800 + 1662.8 = 2462.8  J

Hence we can conclude that the work W for the process Ca = 2462.8  J

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Look at the circuit given below. It consists of a cell, a bulb with two terminals X, Y and wires. P, Q, R and S are positions marked. What is the direction of the flow of current? a) PQXYRS b) SRYXQP c) SPQXYR d) PSRYXQ

Answers

The conventions for the current allow to find the result for which is the direction of the current the is circuit is:

It leaves the positive pole, goes to the blue cable, to the light bulb, from there to the red cable and reaches the negative pole.

Current is the movement of electrons in a circuit per unit time.

In an electrical circuit the electrons that have a negative charge leave the negative electrode towards the positive electrode, by convention the current goes in the opposite direction from the positive electrode towards the negative electrode.

When analyzing the given circuit, the current leaves the positive pole at the top of the battery and moves through the blue wire, reaches the light bulb and moves the red wire and reaches the negative pole of the battery.

In conclusion using the conventions for the current we can find the result for which is the direction of the current the is circuit is:

It leaves the positive pole, goes to the blue cable, to the light bulb, from there to the red cable and reaches the negative pole.

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Two satellites are in orbit around a planet. Satellite 1 has a mass of mm and an orbital radius of 2r2r. Satellite has a mass of 2m2m and an orbital radius of rr. If the magnitude of the gravitational force the planet exerts on Satellite 1 is FF, the magnitude of the gravitational force the planet exerts on Satellite 2 is
a) F
b) 1/2F
c) 2F
d) 1/4F

Answers

The magnitude of the gravitational force the planet exerts on Satellite 2 is  1/2F.

We recall that from Newton's law of universal gravitation, the gravitational force is given by;

F =G m1m2/r^2

m1 and m2 are the respective masses

r is the distance of separation.

Let the mass of the planet be M and the mass of the satellite be m. The distance of separation is r.

For satellite 1;

F = GmM/(2r)^2

F = GmM/4r^2

For satellite 2;

F2= G2mM/r^2

Hence, the magnitude of the gravitational force the planet exerts on Satellite 2 is  1/2F.

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23 A 2-kg rock is moving at a speed 6 m/s, What constant force is needed to stop the rock in 7x10-52

Answers

Answer:

Explanation:

Do you mean 7 x 10⁻⁵² seconds? Who can even measure that small a time period?

If that time is incorrect, just redo the math with the correct time to get the force.

An impulse will cause a change of momentum

FΔt = mΔv

F = mΔv/Δt

F = 2(0 - 6)) / (7 x 10⁻⁵² - 0)

F = - 1.7 x 10⁵² N

The magnitude of that force would pretty much crush any rock it hit.

An object falls through the air, gaining speed as it falls. A student claims th
new energy, and so it breaks the law of conservation of energy. Which stat
why the student is incorrect? (1 point)
Energy can be created without breaking the law of conservation
Energy is converted from other forms, not created.
O Equal and opposite amounts of other energy are also created.
O Speed is not related to energy in any way.

Answers

Answer:

Energy is converted from other forms, not created

Explanation:

The ball has a decrease in potential energy which allows the kinetic energy, and therefore speed, to  increase

A rocket has a mass of 600 kg. a What is its weight on Earth where g = 10 N/kg? b At lift-off the rocket engine exerts an upward force of 26 000 N. What is the resultant force on the rocket? What is its initial acceleration?

Answers

Answer:

a) 5000

b) 40m/s this is the right answers

Explanation:

but no so so sure

Two 5 kg potted cacti, one in a black pot and one in a blue pot, slide down a sagging shelf in the same direction with
the same speed.
Which two equations correctly model the momentum of the two-cactus system?

Answers

Answer:

Answers A and D are the correct solution.

Explanation:

Both pots have the same mass and the same velocity vector.

the only difference between A and D is the selection of the reference frame positive direction.

The equation (A) and equation (D) correctly model the momentum of the two-cactus system.

What is momentum?

The product of a particle's mass and velocity is called momentum. Being a vector quantity, momentum possesses both magnitude and direction.

According to Isaac Newton's second equation of motion, the force applied on a particle is equal to the time rate of change of momentum.

Given that: mass of each cactus: m = 5 kg.

And they slide down a sagging shelf in the same direction with the same speed.

In equation (A), both velocities of two cacti are in positive direction whereas, in equation (B), both velocities of two cacti is in negative direction.  Hence, equation (A) and equation (D) correctly model the momentum of the two-cactus system.

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How do we become children of Abraham and sons of God?

Answers

Answer:

we already are.

Explanation:

God created us, and we are the descendants of Abraham. if you want to choose to live against it, you'll be doing something similar to fighting a current. gods love is unfathomable. he is the only true God, and is our father in heaven.

We are the descendants of Abraham and God crest us and loved us.

A metal bar has a volume of 32 cm3. The mass of the bar is 256 g. What is the density of the metal? A. 290 g/cm3 6 B. 8,200 g/cm C. 8.0 g/cm3 O D. 220 g/cm​

Answers

The density of the metal is ρ = 8.0g/cm³.

Why is density important?

The measure of material how densely it is packed together is called density. As the mass per unit volume, it has that definition. Symbol for density: D or Formula for Density: When is the density, m is the object's mass, and V is its volume, the equation is: = m/V.

Because it enables us to predict which compounds will float and which will sink in a liquid, density is a crucial notion. As long as an object's density is lower than the liquid's density, it will often float.

Equation :

To the given equation we have :

mass of the bar = 256g

volume of metal bar = 32cm³

So according to the formula of density

ρ = m/V

So, putting values

ρ = 256g /32cm³

ρ = 8.0g/cm³

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An object in free fall has a velocity of 5m/s in the upward direction. What is the instantaneous velocity of the object one second later?

Answers

Answer:

Explanation:

Near the earth's surface where gravity is approximately 10 m/s² downward

v = u + at

v = 5 + (-10)(1) = -5 m/s

so it has the same speed but in the opposite (downward) direction.

The instantaneous velocity of the object is -4.8 m/s and is directed downwards.

What is meant by instantaneous velocity ?

Instantaneous velocity is defined as the rate of change of position for a given interval of time. And it also represents the direction.

Here,

The object is freely falling.

So, the acceleration of the object is the acceleration due to gravity.

a = g = 9.8 m/s²

Initial velocity of the object, u = 5 m/s  (upward velocity)

Time given, t = 1

Using the first equation of motion,

v = u + at

v = 5 + (-9.8) x 1  

( negative sign is due to it is directed downwards which is opposite to u)

v = -4.8 m/s

That means the instantaneous velocity is directed downwards.

Hence,

The instantaneous velocity of the object is -4.8 m/s and is directed downwards.

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using dimensional analysis find the relation between the velocities of transverse waves produced from the vibration of thin homogeneous string and between the tension in the string and mass per unit length of it.​

Answers

Answer:

[tex]v^2=\frac{T}{M}[/tex]

where v = transverse wave velocity, T = tension in the string, M = mass per unit length.

Explanation:

Dimensional analysis is where you just look at the units and see how they fit within each other.

In this case, all relationships are made using the MLT comparisons, where M stands for Mass, L stands for Length, and T stands for time.

For example, for velocity, we know the SI unit for velocity is [ms⁻¹] which is L¹T⁻¹, we can do the same thing for tension = [N = Kgms⁻²] = M¹L¹S⁻², and for the mass per unit length which we can think of as [Kgm⁻¹] = M¹L⁻¹.

If you play around a little with the powers, you can find a relationship:

[tex]v^2=\frac{T}{M}[/tex]

since:

[L¹T⁻¹]² = L²T⁻² = M¹L¹T⁻² ÷ M¹L⁻¹ = M¹⁻¹L¹⁻⁽⁻¹⁾T⁻² = M⁰L²T⁻² = L²T⁻²

stuck with this one. ​

Answers

Y is the right answer :)


The spring constant of Spring A is twice as great as the spring constant of Spring B. Both springs are stretched the same amount. How does the
force the Spring A applies compare to the force Spring B applies?

Answers

Answer:

FA = 2FB

Force on spring A is twice the Force on spring B

Explanation:

F = kx

FB = (kB)x

FA = (kA)x

FA= (2kB)x

FA = 2(kB)x

FA = 2FB

The force [tex]F_A[/tex] needed to stretch spring A is going to be twice as much as the force [tex]F_B[/tex] needed to stretch spring B.

Explanation:

We know that the spring constants are related as

[tex]k_A = 2k_B[/tex]

The force [tex]F_A[/tex] needed to stretch spring A is given by

[tex]F_A = -k_Ax[/tex]

Also, the force [tex]F_B[/tex] needed to stretch spring is

[tex]F_B = -k_Bx[/tex]

Taking the ratio of the forces, we get

[tex]\dfrac{F_A}{F_B} = \dfrac{-k_Ax}{-k_Bx} = \dfrac{k_A}{k_B}[/tex]

Since [tex]k_A = 2k_B,[/tex] the equation above becomes

[tex]\dfrac{F_A}{F_B} = \dfrac{2k_B}{k_B} = 2[/tex]

or

[tex]F_A = 2F_B[/tex]

This shows that since the spring constant of spring A is twice as large as that of spring B, the force needed is going to be twice as large.

A runner of mass 80 kg is moving at 8.0 m/s. Calculate her kinetic energy. ​

Answers

Answer:

2560J

Explanation:

By definition the kinetic energy can be calculated in the following way:

K = (mv²)/2 = 80kg·(8.0m/s)²/2 = 2560 J

ur mom walked into a store and got milk

Answers

Answer:

is there any questions

Answer:

What is your question???

Explanation:

An RLC circuit is used in a radio to tune into the radio lagos fm Station broadcasting at 93.5Hz. The resistance is 15ohms and the inductance is 1.6 H. Calculate the capacitance used​

Answers

The characteristics of the RLC circuit allow to find the result for the capacitance at a resonance of 93.5 Hz is:

Capacitance is C = 1.8 10⁻⁶ F

A series RLC circuit reaches the maximum signal for a specific frequency, called the resonance frequency, this value depends on the impedance of the circuit.

            [tex]Z^2 = R^2 + ( wL - \frac{1}{wC} )^2[/tex]  

Where Z is the impedance of the circuit, R the resistance, L the inductance, C the capacitance and w the angular velocity. The negative sign is due to the fact that the current in the capacitor and the inductor are out of phase.

In the case of resonance, the impedance term completes the circuit as a resistive system.

           [tex]wL - \frac{1}{wC} = 0 \\w^2 = \frac{1}{LC}[/tex]  

           

Indicate that the inductance L = 1.6 H and the frequency f = 93.5 Hz.

Angular velocity and frequency are related.

         

         w = 2π f

           

Let's  substitute.

          [tex]C = \frac{1}{L ( 2 \pi f)^2 }[/tex]  

 

Let's calculate.

         [tex]C = \frac{1}{1.6 \ ( 2\pi \ 93.5)^2}[/tex]  

         C = 1.8 10⁻⁶ F

In conclusion with the characteristics of the RLC circuits we can find the result for the capacitance at a 93.5 Hz resonance is:

Capacitance is C = 1.8 10⁻⁶ F

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A particle starts from the origin at t = 0 with a velocity of 6.0 m/s and moves in the xy plane with a constant acceleration of (-2.0 + 4.0) m/s2. At the instant the particle achieves its maximum positive x coordinate, how far is it from the origin

Answers

Answer:

9sqrt4

Explanation:

Assuming you mean 6.0i m/s and (-2.0i + 4.0j) m/s^2:

The maximum positive x coordinate is when the time is 3 seconds, because the horizontal velocity will be zero, and therefore will be a turning point, where after that point the x coordinate will only be more negative.

After 3 seconds the x coordinate is 6*3+1/2*-2*3^2=9, and the y coordinate will be 1/2*4*3^2=18.

The distance from the origin is sqrt(9^2+18^2) = 9*sqrt(1+4)

At the instant the particle achieves its maximum positive x coordinate, the displacement is 4.03 m.

Displacement of the particle

The displacement of the particle is calculated as follows;

v² = u² + 2as

where;

a is acceleration

a = √(2² + 4²) = 4.47 m/s²

0 = u² + 2as

s = -u²/2a

s = -(6²)/(2 x 4.47)

s = -4.03 m

Thus, at the instant the particle achieves its maximum positive x coordinate, the displacement is 4.03 m.

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A constant force of 12 N in the positive x direction acts on a 4.0-kg object as it moves from the origin to the point 6i-8j m. How much work is done by the given force during this displacement

Answers

Answer:

Explanation:

Only force in the direction of motion does work

The force acts in the x direction

The x change of position was 6 m

W = Fd = 12(6) = 72 J

The work done by the given force during this displacement is determined as 120 J.

Work done on the object

The work done on the object is calculated as follows;

W = Fd

where;

d is the displacement of the object

d = √(6² + 8²)

d = 10 m

W = 12 x 10

W = 120 J

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It takes about 4.4 Newtons to lift 1 pound.
How many Newtons would it take to lift 2 pounds?

Answers

it takes 8.8 newtons to lift 2 pounds

If it takes 4.4 Newton to lift 1 pound, then to lift 2 pounds the force required will be equal to 8.8 Newton.

What is Force?

A force in physics is an input that has the power to change an object's motion. A mass-containing object's velocity can vary, or accelerate, as a result of a force. Intuitively, a push or a pull can also be used to describe forces.

Being such a vector quantity, a force does have magnitude and direction. The SI unit metric newton is used to measure it (N). The letter F stands for force.

According to Newton's second law's original formulation, an object's net force is equal to the speed that its momentum is changing over time.

As per the given data in the question,

It takes 4.4 N to lift 1 pound,

Let the total force required to lift 2 pounds is x.

x = (4.4 × 2)/1

x = 8.8 N

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If a wave is traveling at a constant speed, and the frequency decreases, what would happen to the wavelength?

A. It would increase.

B. It would decrease.

C. It would remain constant.

D. It would drop to zero.

Answers

It would decrease because the frequency is decreasing

A train travels at 40m/s. Calculate the time it takes to travel:
A) 30,000 m
B) 50 km

Answers

Answer:

a is 750 second

b is 2 hour

The time it takes for the train to travel 30,000m and 50,000m is 750seconds and 1250 seconds, respectively.

What is speed?

The speed is the distance covered by an object at a particular time. Therefore, it is the ratio of distance and time.

[tex]\rm{Speed = \dfrac{Distance}{Time}[/tex]

A train travels at 40m/s. Now, the time it takes to travel the given distance is,

A.) 30,000m

Speed = Distance / Time

Time = Distance / Speed

Time = 30,000m / 40m/s

Time = 750 seconds

B.) 50 km

1 km = 1000m

50 km = 50 × 1000m = 50,000 m

Speed = Distance / Time

Time = Distance / Speed

Time = 50,000m / 40m/s

Time = 1250 seconds

Hence, the time it takes for the train to travel 30,000m and 50,000m is 750seconds and 1250 seconds, respectively.

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when do we say a curvilinear motion is accelerated?​

Answers

Answer:

There always is an acceleration in a curvilinear motion, as the velocity vector changes, so always.

what forces would a person inside an elevator feel when it is going up?

Answers

Hey there.

So there are a few forces that act upon a person in an elevator. The first is Gravity. This is the downward force keeping us on the floor of the elevator. The second, is the upward force from where the cable takes the elevator upwards. The tension which is present means that for a short period of time, we are pushed into the floor more and our mass goes up.

Hope this helps :)

Why is visual constancy important?

A.
It gives people the ability to see things both close up and far away.

B.
It lets people of all ages see the edges of cliffs so they don’t fall over.

C.
It allows perceptions to remain the same even as images change.

D.
It offers the chance to use one retina at a time to interpret an image.

Reset

Answers

Answer:

C.

Explanation:

Visual constancy is a key mechanism that allows the perception to remain.the same even as images change

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Visual constancy is  important because it allows perceptions to remain the same even as images change.

What is  Constancy phenomenon?

Constancy phenomenon describes how people and animals tend to perceive familiar objects as having a constant shape, size, colour, or location regardless of adjustments to distance, illumination, or perspective. Instead of responding to the real stimulus, the impression has a tendency to adapt to the object as it is or is imagined to be.

The ability to recognise things in a variety of situations, which appear to be "taken into account" throughout a process of mental rebuilding of the known image, is a result of perceptual constancy. For instance, snow appears white in both the dim moonlight and the 800,000-fold brighter day. Reduced contextual cues that help with object identification and limited experience with the object both affect perceptual constancy.

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Which law of motion uses the formula mass = force x acceleration?

Answers

Answer:

Newton's second law

Explanation:

7. Cellular respiration that uses oxygen is called ​

Answers

Answer:

Cellular respiration that uses oxygen is called ​Cellular respiration

Explanation:

Without oxygen, it's call fermentation.

Convert the decimal number 61078 to binary by using sum-of-weights method​

Answers

Answer:

1110111010010110

Explanation:

I am not able to upload the working out using the sum of weights method sorry

A 3.1 kg ball is dropped from the top of a 38 m tall building. What is the speed of the ball when it is halfway from the building to the ground? Round your answer to 2 decimal places.

Answers

Answer:

19.3m/s

Explanation:

Use third equation of motion

[tex]v^2-u^2=2gh[/tex]

where v is the velocity at halfway, u is the initial velocity, g is gravity (9.81m/s^2) and h is the height at which you'd want to find the velocity

insert values to get answer

[tex]v^2-0^2=2(9.81m/s^2)(38/2)\\v^2=9.81m/s^2 *38\\v^2=372.78\\v=\sqrt[]{372.78} \\v=19.3m/s[/tex]

Specific heat capacity
of a solid

Answers

specific heat of a solid or liquid is the amount of heat that raises the temperature of a unit mass of the solid through 1° C. We symbolise it as C. In S.I unit, it is the amount of heat that raises the temperature of 1 kg of solid or liquid through 1K
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