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

Answer:

19.3 m/s

Take down to be positive.  Given:

Δy = 19 m

v₀ = 0 m/s

a = 9.8 m/s²

Find: v

v² = v₀² + 2aΔy

v² = (0 m/s)² + 2 (9.8 m/s²) (19 m)

v = 19.3 m/s

My camera quality is bad. Sorry..

Answer:

the nuclear fusion process

Explanation:

:)

Answer:

nuclear fusion (not fission)

Explanation:

a p e x :))

Explanation:

A molten steel is in a liquid phase of matter. It has no defined volume of shape at this state. The particles inside this materials in this form is randomized by they are still attached to each other.

Answer:

False

Explanation:

A single concave lens has the opposite effect of a magnifying glass.

Answer:

4

Explanation:

because people could lie about it

Answer:

Revolutions

Explanation:

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

Answer:

[tex]a=12.97\ m/s^2[/tex]

Explanation:

Given that,

The length of a string, l = 0.87 m

Speed of the ball, v = 3.36 m/s

We need to find the acceleration of the ball. The acceleration acting on the ball is centripetal acceleration. It is given by :

[tex]a=\dfrac{v^2}{r}\\\\a=\dfrac{(3.36)^2}{0.87}\\\\=12.97\ m/s^2[/tex]

So, the acceleration of the ball is [tex]12.97\ m/s^2[/tex].

Answer:

85.77 m

Explanation:

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

Initial velocity (u) = 41 m/s

Final velocity (v) = 0 m/s (at maximum height)

Acceleration due to gravity (g) = 9.8 m/s²

Maximum height (h) =?

The maximum height reached by the ball can be obtained as follow:

v² = u² – 2gh (since the ball is going against gravity)

0² = 41² – (2 × 9.8 × h)

0 = 1681 – 19.6h

Collect like terms

0 – 1681 = –19.6h

–1681 = –19.6h

Divide both side by –19.6

h = –1681 / –19.6

h = 85.77 m

Thus, the maximum height reached by the ball is 85.77 m

Answer:189000J

Explanation:KE=1/2mv^2

1/2(420g)(30m/s)^2

=189000J

Mass of book will be m = 4.495 kg  

The force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface is called gravitational force

Force = 2.68 x 10-8 N

mass of student(M)  = 55

mass of book=?

distance = 0.435m

gravitational constant (G)=6.67×10^-11

gravitational force (F)=2.68×10^-8

gravitational force (F) = (G*M*m) /[tex]d^{2}[/tex]

2.68 x 10-8  = ((6.67×10^-11) * ( 55 ) * m) / 0.435

m = 4.495 kg

Mass of book will be m = 4.495 kg  

learn more about gravitational force  

https://brainly.com/question/12528243?referrer=searchResults

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Answer:

acellus students

Explanation

1.382

Answer: 10

Explanation:

The mechanical advantage of that pulley is 10.

The force amplified by utilizing a tool, mechanical device, or machine system is known as mechanical advantage. To achieve the desired output force amplification, the gadget trades off input forces against movement. The law of the lever serves as a paradigm for this.

Mechanisms are machine parts made to control forces and motion in this way.

Given that: the weighs of the object: W = 100 Newton.

Applied force: F = 10 N.

For using a pulley, you have to apply a force of 10 Newtons to lift  an object that weighs 100 Newtons.

Hence, the mechanical advantage of the pulley is

= Weighs of the object/applied force

= 100 Newton / 10 Newton.

= 10.

The mechanical advantage of it is 10.

Learn more about mechanical advantage here:

https://brainly.com/question/16617083

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Answer:

i think its 8.2

Explanation:

Answer:

Radiation is used in monitoring the response of tumors to treatment and in distinguishing malignant tumors from benign ones. Bone and liver scans can detect cancers that have spread to these organs. Half of all people with cancer are treated with radiation, and the number of those who have been cured continues to rise.

Explanation:

''.''

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

Answer:

* far from one of the charges, the field of the other charge is small and can be neglected

* on the outside of the loads the fields are added territorially

* between the charges the two fields tend to vanish

Explanation:

The electric field around two objects with charge of the same sign, for simplicity suppose that the objects have positive point spherical charges,

          E = k q / r2

bold letters indicate vectors, therefore the total electric field is

           E_total = E1 + E2

the module of this field is

           E_total = E1- E2

therefore we can outline this field

* far from one of the charges, the field of the other charge is small and can be neglected

* on the outside of the loads the fields are added territorially

* between the charges the two fields tend to vanish

An outline of these shows in Attachment A

The equipotential surfaces are defined as being perpendicular to the electric field lines since the electric field and the power difference are related

              E = [tex]\frac{dV}{dx} i^ + \frac{dV}{dy} j^ + \frac{dV}{dz} k^ = \Delta V[/tex]

We can schematize some characteristics of these surfaces

* very close to each load are spherical surfaces

* very far from the load is an elliptical surface, which envelops the loads

* between them there is a point of zero potential point C

See attached part B

Answer:

The original analog sound waves are perfect but the copy is not because most analog waves have wavelengths that are too long to reproduce in copies

The original digital waves and the copy are perfect because with digital waves no information gets lost in the transfer of data, and there is no additional noise added to the copy.

Analog refers to audio recorded using methods that replicate the original sound waves. Digital audio is recorded by taking samples of the original sound wave at a specified rate.

Explanation:

i dont need $5

i wrote this using information from go ogle and some from brai nly. I hope it helps.

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%

Answer:

6.45×10¯²⁶ J

Explanation:

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

Frequency (f) = 97.3 MHz

Energy (E) =?

Next, we shall convert 97.3 MHz to Hz. This can be obtained as follow:

1 MHz = 1×10⁶ Hz

Therefore,

97.3 MHz = 97.3 MHz × 1×10⁶ Hz / 1 MHz

97.3 MHz = 9.73×10⁷ Hz

Thus, 97.3 MHz is equivalent to 9.73×10⁷ Hz.

Finally, we shall determine the energy at which the frequency is broadcasting. This can be obtained as follow:

Frequency (f) = 9.73×10⁷ Hz

Planck's constant (h) = 6.63×10¯³⁴ Js

Energy (E) =?

E = hf

E = 6.63×10¯³⁴ × 9.73×10⁷

E = 6.45×10¯²⁶ J

Therefore, the energy at which the frequency is broadcasting is 6.45×10¯²⁶ J

Complete question is;

What is the electrical potential at the surface of gold nucleus? The radius of a gold atom is 6.6 × 10​^(-5) m and atomic number z = 79.

Answer:

172.36 × 10^(-5) V

Explanation:

We are given;

Radius; r = 6.6 × 10^(-5) m

Atomic number; Z = 79

Formula for Electric potential here is;

V = kZe/r

Where;

e is charge on proton = 1.6 × 10^(-19) C

k has a constant value of 9 × 10^(9) N⋅m²/C²,

​Thus;

V = (79 × 1.6 × 10^(-19) × 9 × 10^(9))/(6.6 × 10^(-5))

V = 172.36 × 10^(-5) V

Answer:

A. 1600 kilojoules

Explanation:

Looking at the graph, at 4 meters, we can guess the energy transferred would be around 1500 kilojoules. 1600 kilojoules is the closest to that value, so A would be the best choice.

Answer:

12 N/cm²

Explanation:

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

Weight (W) of block = 240 N

Area (A) = 20 cm²

Pressure (P) =?

Next, we shall determine the force exerted by the block. This can be obtained as follow:

Weight (W) of block = 240 N

Force (F) =.?

Weight and force has the same unit of measurement. Thus, we force applied is equivalent to the weight of the block. Thus,

Force (F) = Weight (W) of block = 240 N

Force (F) = 240 N

Finally, we shall determine the pressure on the floor as follow:

Force (F) = 240 N

Area (A) = 20 cm²

Pressure (P) =?

P = F/A

P = 240 / 20

P = 12 N/cm²

Therefore, the pressure on the floor is 12 N/cm².

Answer:

20g

Explanation:

Given parameters:

Quantity of heat  = 240calories

Initial temperature  = 80°C

Final temperature  = 68°C

Unknown:

Mass of water = ?

Solution;

To solve this problem, we use the expression:

         Q  = m c (t₂  - t₁)

Q is the quantity of heat

m is the mass

c is the specific heat = 1 cal/g°C

t₂ is the final temperature

t₁ is the initial temperature

  Insert the parameters and solve;

  Change in temperature is an absolute value

          240 = m x 1 x (68 - 80)

           m  = 20g

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

Answer:

 F_A = 8 F_B

Explanation:

The force exerted by the planet on each moon is given by the law of universal gravitation

        F = [tex]G \frac{m M}{r^{2} }[/tex]

where M is the mass of the planet, m the mass of the moon and r the distance between its centers

let's apply this equation to our case

Moon A

the distance between the planet and the moon A is r and the mass of the moon is 2m

        F_A = G \frac{2m M}{r^{2} }

Moon B

        F_B = G \frac{m M}{(2r)^{2} }

         F_B = G \frac{m M}{4 r^{2} }

the relationship between these forces is

         F_B / F_A = [tex]\frac{1}{2 \ 4 }[/tex] = 1/8

         F_A = 8 F_B

Answer:

F_A = 8 F_B

Explanation:

The force exerted by the planet on each moon is given by the law of universal gravitation

       F =

where M is the mass of the planet, m the mass of the moon and r the distance between its centers

let's apply this equation to our case

Moon A

the distance between the planet and the moon A is r and the mass of the moon is 2m

       F_A = G \frac{2m M}{r^{2} }

Moon B

       F_B = G \frac{m M}{(2r)^{2} }

        F_B = G \frac{m M}{4 r^{2} }

the relationship between these forces is

        F_B / F_A =  = 1/8

        F_A = 8 F_B

Answer:

Magnetic Field

Explanation:

Answer:

Magnetic field

Explanation: