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luda_lava [24]
3 years ago
12

Mary starts from her house, walks 80 meters south, and stops to chat with her aunt on the sidewalk. After chatting for a few min

utes, she walks 125 meters to the west to meet a friend and then walks 45 meters north with her friend to a cafe for lunch. Overall, she takes 10 minutes to do all this. What is Mary’s average speed?Select one of the options below as your answer: A. 8 meters/second B. 1.25 meters/second C. 25 meters/second D. 4.5 meters/second E. 0.42 meters/second
Physics
1 answer:
marin [14]3 years ago
5 0
Mary walks:
d 1 = 80 m,  d 2 = 125 m,  d 3 = 45 m
t = 10 minutes = 600 seconds;
Average speed:
v = ( d 1 + d 2 + d 3 ) / t 
v = ( 80 m + 125 m + 45 m ) / 600 s
v = 250 m / 600 s
v = 0.4167 m/s ≈ 0.42 m/s
Answer:
E ) 0.42 meters/second
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A flat sheet of ice has a thickness of 1.4 cm. It is on top of a flat sheet of crown glass that has a thickness of 3.0 cm. Light
MAXImum [283]

Answer:

t = 2.13 10-10 s , d = 6.39 cm

Explanation:

For this exercise we use the definition of refractive index

        n = c / v

Where n is the refraction index, c the speed of light and v the speed in the material medium.

The refractive indices of ice and crown glass are 1.13 and 1.52, respectively, therefore the speed of the beam in the material medium is

        v = c / n

As the beam strikes perpendicularly, the beam path is equal to the distance of the leaves, there is no refraction, so we can use the uniform motion relationships

        v = d / t

        t = d / v

        t = d n / c

Let's look for the times on each sheet

Ice

        t₁ = 1.4 10⁻² 1.31 / 3 10⁸

        t₁ = 0.6113 10⁻¹⁰ s

Crown glass (BK7)

        t₂ = 3.0 10⁻² 1.52 / 3.0 10⁸

        t₂ = 1.52 10⁻¹⁰ s

Time is a scalar therefore it is additive

         t = t₁ + t₂

         t = (0.6113 + 1.52) 10⁻¹⁰

         t = 2.13 10-10 s

The distance traveled by this time in a vacuum would be

        d = c t

       d = 3 10⁸ 2.13 10⁻¹⁰

       d = 6.39 10⁻² m

       d = 6.39 cm

3 0
3 years ago
light of a certain frequency has a wavelength of 438 nm in water.What is the wavelength of this light in benzene​
sveticcg [70]

Answer:

388.97 nm

Explanation:

The computation of the wavelength of this light in benzene is shown below:

As we know that

n (water) = 1.333

n (benzene) = 1.501

\lambda (water) \times n(water) = \lambda (benzene) \times n(benzene)

And, the wavelength of water is 438 nm

\lambda (benzene) = \lambda (water) [\frac{n(water)}{n(benzene}]

Now placing these values to the above formula

So,

= 438 \times \frac{1.333}{1.501}

= 388.97 nm

We simply applied the above formula so that we can easily determine the wavelength of this light in benzene​ could come

5 0
3 years ago
A force of 45 newtons is applied on an object, moving it 12 meters away in the same direction as the force. What is the magnitud
klio [65]

If the applied force is in the same direction as the object's displacement, the work done on the object is:

W = Fd

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Given values:

F = 45N

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Plug in and solve for W:

W = 45(12)

W = 540J

5 0
3 years ago
What is the relationship between the masses of the objects and the gravitational force between them
irga5000 [103]

The relationship between the masses of the object and the gravitational force between them is a direct relationship

Explanation:

The gravitational force between two objects is given by  the equation:

F=G\frac{m_1 m_2}{r^2}

where

G=6.67\cdot 10^{-11} m^3 kg^{-1}s^{-2} is the gravitational constant

m1, m2 are the masses of the two objects

r is the separation between them

We observe that:

- The gravitational force is proportional to the masses of the two objects, m1 and m2, so if the masses increase, the force will increase as well (so, this is a direct relationship)

- The gravitational force is inversely proportional to the square of the separation between the objects, so if the distance is increased, the force will decrease (so, this is an inverse relationship)

Learn more about gravitational force here:

brainly.com/question/1724648

brainly.com/question/12785992

#LearnwithBrainly

6 0
3 years ago
Speed of 26.7 m/s in 3.06 s. How far had the car traveled by the time the final speed was achieved?
Alik [6]

Answer:

Below

Explanation:

You can use this equation to find the distance :

     distance = velocity x time

     distance = (26.7)(3.06)

                    = 81.702 m

Rounding to 3 sig figs

     = 81.7 m

Hope this helps

6 0
2 years ago
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