A construction laborer holds a 20 kg sheet of wallboard 3 m above the floor for 4 seconds. During these 4 seconds how much power was expended on the wallboard

Answers

Answer 1

Answer:

zero

Explanation:

no distance has moved while holding the sheet...so no distance means no workdone..no workdone means no power...


Related Questions

let's say you hypothetically ran over someone with your car, and they are now under your car in between the front wheels and the back wheels, right, and they're stuck as in can't breathe type stuck, right, do you keep driving so they can breathe or do you let them chill under your car?
just curious...​

Answers

question: is this actually hypothetical?

Explanation:

also just leave the car there go get some McDonald's or sum and come back and if they're still breathing then go ahead and move the car .

Answer:

the same thing the last guy said

A student is creating an electromagnet for an investigation. Which feature of the electromagnet will least influence the magnetic force?
A
the material of the core
B
the brand of the battery
С
the number of wire coils
D
the che of the power source

Answers

C the number of wire coils

Two identical plastic cups contain the same amount of water at two different temperatures, as shown to the left. Both cups are placed in a room at 25° Celsius. At the time cups were placed in the room, in which cup do the water molecules have higher average kinetic energy? ( Cup 1 © Cup 2​

Answers

Answer:

the molecules will begin to move slowly and will turn to ice

Explanation:

hope this was good or not not sure if am right but yeah

How will a metal container full of hot water in vaccum lose heat?​

Answers

Hey I hope you had some fun with me I love y’all so I’m gonna have a great time with your friends and I love y’all too babe I hope you have some great time love y’all babe I hope you have some great time love y’all love love?

Marvin the Martian needs to get back home. Marvin is 321,770 m from his home on Mars. He decides the quickest way to get home is to use his canon to fire himself into flight. He aims the the canon at an angle of 25 degrees. When the canon is fired Marvin the Martian is launched into flight at an initial velocity of 1250 m/s. The question is will his plan work

Answers

Answer:

y = 14238 m.    the height of the rocket is much less than this distance therefore the plan will not work.

Explanation:

Let's analyze this exercise, so that the Martian's plan works, the vertical height of the body must be zero when it is more than half of the way to the planet Mars, this is so that Mars attracts it and can arrive.

Let's calculate the maximum height of the launch

          [tex]v_{y} ^2 = v_{oy}^2 - 2 g y[/tex]

at the highest point [tex]v_{y}[/tex] = 0

          y = v_{oy}² / 2g

          y = (v₀ sin θ)² / 2g

let's calculate

          y = (1250 sin 25)² /2 9.8

          y = 14238 m

In the exercise, indicate that the distance to Mars is h = 321770 m, half of this distance is

          h / 2 = 160885 m

therefore the height of the rocket is much less than this distance therefore the plan will not work.

The height reached is low, so it is not necessary to take into account the variation of g with height

A 4 kg bowling bowl is sitting on a table 1 meter off the ground. How much potential energy does it have?

Answers

Answer:

[tex]\huge\boxed{\sf P.E. = 39.2\ Joules}[/tex]

Explanation:

Given Data:

Mass = m = 4 kg

Acceleration due to gravity = g = 9.8 m/s²

Height = h = 1 m

Required:

Potential Energy = P.E. = ?

Formula:

P.E. = mgh

Solution:

P.E. = (4)(9.8)(1)

P.E. = 39.2 Joules

[tex]\rule[225]{225}{2}[/tex]

Hope this helped!

~AH1807

how are hydrosphere, atmosphere, Biosphere, and Biosphere connected to one another

Answers

Explanation:

Such spheres are intimately connected. Many animals (biosphere), for example, migrate through to the sky, while groundwater (hydrosphere) also flows through the ground (lithosphere). The domains are actually so closely related that a shift in one globe always results in a shift in one or both of some other spheres.

An automobile which set the world record for acceleration increase speed from rest to 96 km/h in 3.07 seconds what distance traveled by the time the final speed was achieved

Answers

Answer:

41.02m

Explanation:

Given parameters:

Initial velocity = 0m/s

Final velocity  = 96km/hr

Time taken  = 3.07s

Unknown:

Distance traveled by the time the final speed was achieved = ?

Solution:

To solve this problem, we first find the acceleration of the car;

     Acceleration  = [tex]\frac{v - u }{t}[/tex]

v is the final velocity

u is the initial velocity

t is the time taken

  Now convert the the final velocity to m/s;

          96km/hr to m/s;

               1 km/hr  = 0.278m/s

               96km/hr  = 96 x 0.278 = 26.7m/s

Now;

 Acceleration  = [tex]\frac{26.7 - 0}{3.07}[/tex]   = 8.69m/s²

So;

   v²  = u²  + 2as

v is the final velocity

u is the initial velocity

a is the acceleration

s is the distance

             26.7²  = 0²  + 2 x 8.69 x s

             712.89  = 17.38s

                  s  = 41.02m

A(n) 636 kg elevator starts from rest. It moves upward for 4.5 s with a constant acceleration until it reaches its cruising speed of 2.05 m/s. The acceleration of gravity is 9.8 m/s 2 . Find the average power delivered by the elevator motor during this period. Answer in units of kW.

Answers

Answer:

The average power delivered by the elevator motor during this period is 6.686 kW.

Explanation:

Given;

mass of the elevator, m = 636 kg

initial speed of the elevator, u = 0

time of motion, t = 4.5 s

final speed of the elevator, v = 2.05 m/s

The upward force of the elevator is calculated as;

F = m(a + g)

where;

m is mass of the elevator

a is the constant acceleration of the elevator

g is acceleration due to gravity = 9.8 m/s²

[tex]a = \frac{v-u}{t} \\\\a = \frac{2.05 -0}{4.5} \\\\a = 0.456 \ m/s^2[/tex]

F = (636)(0.456 + 9.8)

F = (636)(10.256)

F = 6522.816 N

The average power delivered by the elevator is calculated as;

[tex]P_{avg} = \frac{1}{2} (Fv)\\\\P_{avg} = \frac{1}{2} (6522.816 \ \times \ 2.05)\\\\P_{avg} = 6685.89 \ W\\\\P_{avg} = 6.68589 \ kW\\\\P_{avg} = 6.686 \ k W[/tex]

Therefore, the average power delivered by the elevator motor during this period is 6.686 kW.

Two hockey pucks with mass 0.1 kg slide across the ice and collide. Before
the collision, puck 1 is going 15 m/s to the east and puck 2 is going 12 m/s to
the west. After the collision, puck 2 is going 15 m/s to the east. What is the
velocity of puck 1?

Answers

Answer:

Puck 1 = 12 m/s

Explanation:

Conservation of energy

KE_1a + KE_2a = KE_1b + KE_2b

(1/2)(0.1kg)(15m/s)^2 + (1/2)(0.1kg)(12m/s)^2 = (1/2)(0.1kg)(V)^2 + (1/2)(0.1kg)(15m/s)^2

V = 12m/s

Answer:

12 m/s west

Explanation:

just did it

two cars with initial speed 2v and v, lock their brakes and skid to a stop. what is the ratio of the distance travelled

Answers

Answer:

4:1

Explanation:

Given that the initial speed of the first car, u = 2v while the initial speed of the second car, u = v. To find the distance travelled, we are going to apply one of the equations of motion. The equation chosen is

v² = u² - 2as, where

s = the distance needed

a = acceleration due to gravity

u = initial velocity which is v & 2v

v = final velocity which is 0

For the first car with initial velocity, 2v, on substituting into the equation, we have

v² = u² - 2as(1)

0 = 4v - 2as(1)

4v = 2as(1)

2v = as(1), making s(1) subject of formula we have

s(1) = 2v/a

Taking the second car, we have u = v

v² = u² - 2as(2)

0 = v - 2as(2)

v = 2as(2), making s(2) subject of formula, we have

s(2) = v/2a

Not, ratio of s1 : s2 =

2v/a : v/2a

s1/s2 = 2v/a ÷ v/2a

s1/s2 = 2v/a * 2a/v

s1/s2 = 4av/av

s1/s2 = 4/1

Therefore, the ratio of the first car to the second car is 4:1

Please leave a like if it helped you

The least count of stopwatch is 0.2s.The time of 20 oscillations of a pendulum was measured to be 25s.Find the percentage error in the measurement of time​

Answers

Answer:

0.8%

Explanation:

We are given;

Number of oscillations; n = 20

Time taken; t = 25 s

Formula for period of oscillation;

T = t/n = 25/20 = 1.25 s

We are told that the least count is 0.2 s. Thus, error is; ΔT = 0.2 s

percentage error in the measurement of time is given by;

(0.2/(20 × 1.25)) × 100% = 0.8%

Which type of telescope is best used to detect distant planets?​

Answers

I believe the answer would be, refractor type telescopes because these are best used for planetary observations.


Define friction. Prove that tangent of angle of friction is equal to coefficient
of friction.​

Answers

Answer:

Friction is the force that opposes movement between moving objects.

The angle at which one object starts to slip on the other is directly related to the coefficient. When the two objects are horizontal there is no frictional force. So, the coefficient of static friction is equal to the tangent of the angle at which the objects slide. A similar method can be used to measure μk.

Explanation:

Answer:

brainliest plsssssss

Explanation:

The resistance that one surface or object encounters when moving over another

write the difference between convert and
Concave minores​

Answers

A concave mirror is opaque whereas a concave lens is transparent. ... Difference between concave mirror and concave lens is A concave mirror is opaque whereas a concave lens is transparent. A concave mirror causes reflection of light whereas a concave lens causes refraction of light.

which of the following is not a mechanical form of energy?
a. Nuclear
b. Kinetic
c. Spring potential
d. Gravitational potential ​

Answers

Answer:

The answer is Spring Potential

Explanation:

Because all the others are a mechanical form of energy

Deshaun Watson launches a football at a speed of 24.7 ms and an angle of 33° above the horizontal How far down
the football field does the football land? What is the max height the football reaches during flight?
Show work

Answers

Answer:

9.23m

Explanation:

Max height = u²sin²theta/2g

u is the speed = 34.7m/s

theta is the angle of elevation = 33°

g is the acceleration due to gravity = 9.8m/s²

Substitute into the formula

Max height = 24.7²sin²33/2(9.8)

Max height = 610.09sin²33/2(9.8)

Max height = 610.09(0.29663)/19.6

Max height = 180.97/19.6

Max Height = 9.23m

Hence the max height the football reaches during flight is 9.23m

A horizontal force of 90.7 N is applied to a 40.5 kg crate on a rough, level surface. If the crate accelerates at 1.08 m/s, what is the magnitude of the force of kinetic friction (in N) acting on the crate?

Answers

Mhide,

if the mass of 60 kg is having an acceleration of 1.2 m/s², we have:

F = m . a

60 x 1.2 = 72 N

That is, the resultant force is 72 newtons.

If the applied force is 95 N, we come to the conclusion that 95 - f = 72

Or,

f = 23 newtons, or 23 N, of kinetic friction.

A boat is drifting to the right with a speed of 5.0 m/s when the driver turns on the motor. The motor runs for 6.0 seconds causing a constant leftward acceleration of magnitude 4.0 m/s squared. What is the displacement of the boat over the 6.0 second time interval?

Answers

Answer:

[tex]D= -0.42km[/tex]

Explanation:

From the question we are told that

Drifting right with speed 5.0m/s

The motor runs for 6.0 seconds

Leftward acceleration of magnitude 4.0 m/s squared

Generally the equation [tex]V=ut+1/2at^2[/tex] can be used here

[tex]V=ut+1/2at^2[/tex]

Mathematically solving with the newton equation above we have that

   [tex]D=5*6 + \frac{1}{2} (-4)*6^2[/tex]

   [tex]D=30-72[/tex]

   [tex]D=-42m[/tex] [tex]or -0.42km[/tex]

Therefore having this the Displacement is [tex]D= -0.42km[/tex] leftward

What happens to most of the light waves that strike a clear pane of glass? O A. absorption B. diffraction O C. reflection O D. transmission​

Answers

slight reflect but most goes through because glass is transparent

Most of the light waves that strike a clear pane of glass reflects. Details about reflection can be found below.

What is reflection?

Refection in physics is the property of a propagated wave being thrown back from a surface such as a mirror.

Mirror is an example of an object that could be hit by an incumbent wave, however, most of the light waves that hit the mirror surface gets reflected back.

Therefore, most of the light waves that strike a clear pane of glass reflects.

Learn more about refection at: https://brainly.com/question/15487308

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What 2 factors do you need in order to calculate speed?

Answers

Answer:

Distance and time.

Explanation:

Speed=Distance/time

The two factors which we need in order to calculate the speed of an object are the distance covered by the object and the time taken to cover that distance.

What is Speed?

Speed is the rate of change of position of an object in any direction. Speed is a scalar quantity as it has only magnitude and no direction. It is measured as the ratio of the distance covered by an object to the time taken in which the distance was covered by that object.

Speed has the dimension of distance covered by the time taken. Thus, the SI unit of speed is the combination of the basic units of distance and the basic unit of Time. Thus, the SI unit of speed is meter per second (m/s).

Learn more about Speed here:

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An inductor with an inductance of .5 henrys (H) is to be connected to a 60 Hz circuit. What will the inductive reactance (X L) be

Answers

Answer:

1885.2 ohms

Explanation:

Step one:

given data

L=5H

f=60Hz

Required

The inductive reactance of the inductor

Step two:

Applying the expression

XL= 2πfL

substitute

XL=2*3.142*60*5

XL=1885.2 ohms

The metal wire is stretched so that its cross-section is still circular but its total length is now 10 meters. What is the resistance of the wire after stretching

Answers

I don’t know I think about 20 meters but I’m probably wrong I just need to do this so someone can answer my question

A different bullet has a mass of 0.09 kg. Starting from rest, after its gun's trigger is pulled, a constant force acts on the bullet for the next 0.025 seconds until the bullet leaves the barrel of the gun with a speed of 1,346 m/s.

What force acts on this bullet?

Answers

The force acts on this bullet : 4.8456 N

Further explanation

Given

m=0.09 kg

Δt=0.025 s

vo=0(from rest)

vt=1.346 m/s

Required

Force

Solution

Impulse is a change in momentum

I=ΔP

F.Δt=m(vt-vo)

Input the value

F x 0.025 = 0.09(1.346-0)

F=4.8456 N

Determine the absolute pressure on the bottom of a swimming pool 30.0 mm by 8.4 mm whose uniform depth is 1.9 mm .

Answers

Answer:

=101343.62N/m^2

Explanation:

absolute pressure on the bottom of a swimming pool= atmospheric pressure +( 2 ×ρ ×g)

( 2 ×ρ ×g)= guage pressure

atmospheric pressure= 101325pa

h= height= 1.9 mm = 1.9×10^-3m

ρ = density of water

= 1000kg/m^3

g= acceleration due to gravity= 9.8m/s^2

Then substitute, we have

absolute pressure on the bottom of a swimming pool= 101325+ [0.0019 ×1000 × 9.8)]

=101343.62N/m^2

Hence, the absolute pressure on the bottom of a swimming pool is =101343.62N/m^2

Select the correct answer.
Which of these factors will increase the speed of a sound wave in the air?
A. slowing down the movement of particles in the air
B. raising the temperature of the air
C. removing particles form the air
D. decreasing the kinetic energy of the air
E. stopping particle collisions in the air

Answers

Answer:

B

Explanation:

But molecules at a higher temperature have more energy.

Answer: B. Raising the temperature of the air

If the angle between two forces increases, the magnitude of their resultant-
A Decreases
C. Remain unchanged
D. Decrease than decreases​

Answers

A is the answer to your question

Optimus Prime is flying straight up at 24 m/s when he accidentally drops his mega-ray blaster and it falls 94 m to the ground below. Calculate how long it takes for his mega-ray blaster to hit the ground.

Answers

Answer:

The time it will take the mega-ray blaster to hit the ground is 2.57 s.

Explanation:

Given;

initial velocity of Optimus Prime, u = 24 m/s

height of fall of the mega-ray blaster, h = 94 m

The time of fall of the mega-ray blaster is calculated using the following kinematic equation;

[tex]h = ut + \frac{1}{2}gt^2\\\\94 = 24t + \frac{1}{2}(9.8)t^2\\\\94 = 24t + 4.9t^2\\\\4.9t^2 +24t -94 = 0\\\\Use \ formula \ method \ to \ solve \ for \ "t"\\\\a = 4.9 , b = 24, c = -94\\\\t = \frac{-b \ +/- \ \sqrt{b^2 -4ac} }{2a} \\\\t = \frac{-24 \ +/- \ \sqrt{(24)^2 -4(-94 \times4.9)} }{2(4.9)} \\\\t = \frac{-24 \ +/- \ \sqrt{2418.4} }{9.8}\\\\t = \frac{-24 \ +/- \ 49.177 }{9.8}\\\\t = \frac{-24 \ +\ 49.177 }{9.8} \ \ or \ \ t = \frac{-24 \ -\ 49.177 }{9.8} \\\\[/tex]

[tex]t = 2.57 \ s \ \ or \ \ t = -7.47 \ s[/tex]

t = 2.57 s

Therefore, the time it will take the mega-ray blaster to hit the ground is 2.57 s.

( I will give a brainliest )
What must be changed, temperature or heat energy, during condensation?

Answers

Answer:

The answer is temperature lol

Explanation:

:)

Help! Help!

___ are a primary way to discourage drinking and driving.
A. High prices for alcohol
B. Scare tactics
C. Laws

Answers

Answer:

Laws

Explanation:

Laws are a primary way discourage drinking and driving

A primary way to discourage drinking and driving is Law.

What is drinking and driving?

The person who takes in alcohol and then drives on the road. This is strictly prohibited.

Laws against the  'drinking and driving' will make people get scared of getting charged or sentenced to jail for some years. Lot of accidents have caused when there were no laws against the action.

Thus, Laws are a primary way to discourage drinking and driving.

Learn more about drinking and driving.

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