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velikii [3]
3 years ago
11

a man exerts 700 newtons of force to move a piece of furniture 4 meters. if it takes him 2 seconds to move the furniture, how mu

ch power does it require?
Physics
1 answer:
dybincka [34]3 years ago
6 0

                               Work = (force) x (distance)

The work he did:    Work = (700 N) x (4m)  =  2,800 joules

The rate at which
he did it (power):    Work/time =  2,800 joules/2 sec

                                                =  1,400  joules/sec

                                                =  1,400 watts

                                                =  1.877... horsepower (rounded)
 
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n 38 g rifle bullet traveling at 410 m/s buries itself in a 4.2 kg pendulum hanging on a 2.8 m long string, which makes the pend
Kitty [74]

Answer:

68cm

Explanation:

You can solve this problem by using the momentum conservation and energy conservation. By using the conservation of the momentum you get

p_f=p_i\\mv_1+Mv_2=(m+M)v

m: mass of the bullet

M: mass of the pendulum

v1: velocity of the bullet = 410m/s

v2: velocity of the pendulum =0m/s

v: velocity of both bullet ad pendulum joint

By replacing you can find v:

(0.038kg)(410m/s)+0=(0.038kg+4.2kg)v\\\\v=3.67\frac{m}{s}

this value of v is used as the velocity of the total kinetic energy of the block of pendulum and bullet. This energy equals the potential energy for the maximum height reached by the block:

E_{fp}=E_{ki}\\\\(m+M)gh=\frac{1}{2}mv^2

g: 9.8/s^2

h: height

By doing h the subject of the equation and replacing you obtain:

(0.038kg+4.2kg)(9.8m/s^2)h=\frac{1}{2}(0.038kg+4.2kg)(3.67m/s)^2\\\\h=0.68m

hence, the heigth is 68cm

4 0
3 years ago
Materials that are soft and porous will absorb energy causing a decrease in amplitude and energy of the sound. This is called __
Vedmedyk [2.9K]
Damping of the sound
5 0
2 years ago
Can we use momentum to see how fast the earth is going?
Kisachek [45]

Yes, if we know the Earth's mass

Explanation:

The momentum of an object is a vector quantity given by the equation

p=mv

where

m is the mass of the object

v is its velocity

In this case, we are asked if we can find the velocity of the Earth by starting from its momentum. Indeed, we can. In fact, we can rewrite the equation above as

v=\frac{p}{m}

Therefore, if we know the momentum of the Earth (p) and we know its mass as well (m), we can solve the formula to find the Earth's velocity.

Learn more about momentum:

brainly.com/question/7973509

brainly.com/question/6573742

brainly.com/question/2370982

brainly.com/question/9484203

#LearnwithBrainly

6 0
3 years ago
If a steady-state heat transfer rate of 3 kW is conducted through a section of insulating material 1.0 m2 in cross section and 2
kaheart [24]

Answer:

\Delta T = \frac{3000 W *0.025 m}{1 m^2 (0.2 \frac{W}{mK})}= 375 K

So then the difference of temperature across the material would be \Delta T = 375 K

Explanation:

For this case we can use the Fourier Law of heat conduction given by the following equation:

Q = -kA \frac{\Delta T}{\Delta x}   (1)

Where k = thermal conductivity = 0.2 W/ mK

A= 1m^2 represent the cross sectional area

Q= 3KW represent the rate of heat transfer

\Delta T is the temperature of difference that we want to find

\Delta x=2.5 cm =0.025 m represent the thickness of the material

If we solve \Delta T in absolute value from the equation (1) we got:

\Delta T =\frac{Q \Delta x}{Ak}

First we convert 3KW to W and we got:

Q= 3 KW* \frac{1000W}{1 Kw}= 3000 W

And we have everything to replace and we got:

\Delta T = \frac{3000 W *0.025 m}{1 m^2 (0.2 \frac{W}{mK})}= 375 K

So then the difference of temperature across the material would be \Delta T = 375 K

5 0
3 years ago
What is the concentration of H+ ions at a pH = 7? mol/L What is the concentration of OH– ions at a pH = 7? mol/L What is the rat
AnnZ [28]
<h3><u>Answer;</u></h3>

= 0.0000001 mol/L  

= 0.0000001 mol/L  

= 1:1

<h3><u>Explanation;</u></h3>

What is the concentration of H+ ions at a pH = 7?

The formula for ph is given by:

pH=−log10[H+]

In calculating for the concentration of hydrogen ion, the formula is given by:

[H+]=(10)^(-pH)

Therefore; at pH = 7

[H+]=(10)^(-7)

<u>= 0.0000001 mol/L </u> 

What is the concentration of OH– ions at a pH = 7?

pH+pOH=14

7+pOH=14

pOH= 7

[OH-]=(10)^(-pOH)

[OH-]=(10)^(-7)

<u>= 0.0000001 mol/L  </u>

What is the ratio of H+ ions to OH– ions at a pH = 7?  

1:1

8 0
3 years ago
Read 2 more answers
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