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Mars2501 [29]
1 year ago
9

A horizontal force of 140 N is needed to pull a 60kg box across the horizontal floor at constant speed . Find the coefficient of

friction between the floor and box to three significant figures.​
Physics
1 answer:
____ [38]1 year ago
4 0

Explanation:

formula for force is:

force=mass × acceleration

but in case of friction

force =coefficient of friction × Normal Reaction

F. = u × R

U = F/R

but when placed horizontally

R= M×G

M=mass=60kg

G=Gravity(10m/s or 9.8m/s)

F=140N

U=140/60×10

U=140/600

U=0.2333333333

approximately to 3 significant figures

U=0.233

if i am correct rate it 5 star

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An 800-N billboard worker stands on a 4.0-m scaffold weighing 500 N and supported by vertical ropes at each end. How far would t
Lynna [10]

Answer:

2.5 m

Explanation:

Weight of billboard worker = 800 N

Number of ropes = 2

Length of scaffold = 4 m

Weight of scaffold = 500 N

Tension in rope = 550 N

The sum of the torques will be

-800(4-x)-500\times 2+550\times 4=0\\\Rightarrow -800(4-x)=500\times 2-550\times 4\\\Rightarrow -800(4-x)=-1200\\\Rightarrow -x=\dfrac{1200}{800}-4\\\Rightarrow -x=-2.5\\\Rightarrow x=2.5\ m

The position of the person will be 2.5 m

7 0
3 years ago
This is “Fusion Reactions”.<br> Please answer number 8. Thank you.
Angelina_Jolie [31]

Answer:

²₁H + ³₂He —> ⁴₂He + ¹₁H

Explanation:

From the question given above,

²₁H + ³₂He —> __ + ¹₁H

Let ⁿₐX be the unknown.

Thus the equation becomes:

²₁H + ³₂He —> ⁿₐX + ¹₁H

We shall determine, n, a and X. This can be obtained as follow:

For n:

2 + 3 = n + 1

5 = n + 1

Collect like terms

n = 5 – 1

n = 4

For a:

1 + 2 = a + 1

3 = a + 1

Collect like terms

a = 3 – 1

a = 2

For X:

n = 4

a = 2

X =?

ⁿₐX => ⁴₂X => ⁴₂He

Thus, the balanced equation is

²₁H + ³₂He —> ⁴₂He + ¹₁H

8 0
2 years ago
A plece of titanium has a mass of 67.5g and a volume of 15cm<br> What is the density?
sveta [45]

Answer:

4.5g/cm^3

Explanation:

Here, Mass(m)=67.5g

         Volume(v)=15cm^3

Now, According to formula,

        Density(p)=m/v

                         =67.5/15

                         =4.5g/cm^3

8 0
3 years ago
The chart shows data for an object moving at a constant acceleration. Which values best complete the chart? Time (s) Velocity (m
dangina [55]

Answer:

A.

x: 0

y: 0

z: 0

Explanation:

3 0
3 years ago
Read 2 more answers
A sodium atom will absorb light with a wavelength near 589 nm if the light is within 10 MHz of the resonant frequency. The atomi
Troyanec [42]

Answer:

i)20369 photons

ii) 40 ps

Explanation:

Momentum of one Sodium atom:

P=m*v =600m/s*23amu*\frac{1 kg}{6.02*10^{23}amu}\\P=2.29*10^{-23}kgm/s

In other to stop it, it must absorb the same momentum in photons:

P=2.29*10^{-23}kgm/s=n_{photons}*\frac{h_{planck}}{\lambda}\\=n*\frac{6.63*10^{-34}}{589*10^{-9}} \\==>n=20369 photons

Now, for the minimun time, we use the speed of light and the wavelength. For the n photons:

t=n*T=n*\frac{\lambda}{c} =20369*\frac{589nm}{3*10^{8}m/s}=4*10^{-11} second=40 ps

7 0
3 years ago
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