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mariarad [96]
2 years ago
10

The formula d = t² + 5 t expresses a car's distance (in feet) from a stop sign, d, in terms of the number of seconds t since it

started moving.
Determine the car's average speed over the interval of time from t = 4 seconds to t = 7 seconds.
Physics
1 answer:
Lubov Fominskaja [6]2 years ago
3 0

Answer:

The car's average speed is 16 feet per second.

Explanation:

The expression for the average speed is as follows;

A.S=\frac{\textrm{Total distance}}{\textrm{total time}}

Given expression of distance:

d=t^{2}+5t

Put t= 4 s.

d(4)=(4)^{2}+5(4)

d(4)= 36 ft

Put t= 7 s in the given expression.

d(7)=(7)^{2}+5(7)

d(7)= 84 ft

Calculate the car's average speed over the interval of time from t = 4 seconds to t = 7 seconds.

A.S=\frac{d(7)-d(4)}{7-4}

A.S=\frac{84-36}{7-4}

A.S= 16 feet per second

Therefore, the car's average speed is 16 feet per second.

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A jogger hears a car alarm and decides to investigate. While running toward the car, she hears an alarm frequency of 872.10 Hz.
Nata [24]

Answer:

v = 4.18 m/s

Explanation:

given,

frequency of the alarm = 872.10 Hz

after passing car frequency she hear = 851.10 Hz

Speed of sound = 343 m/s

speed of the jogger = ?

speed of the

v_f = \dfrac{872.10-851.10}{2}

v_f =10.5\ Hz

v_o = 872.1 - 10.5

V_0 = 861.6\ Hz

The speed of jogger

v = \dfrac{v_1 \times 343}{v_0}-343

v = \dfrac{872.1 \times 343}{861.6}-343

v = 4.18 m/s

5 0
2 years ago
The index of refraction is the ratio of the speed of light in a vacuum to the speed of light in a medium. Which true statement i
Alika [10]

Answer:

A. Materials with a low index of refraction cause light to refract very little.

7 0
2 years ago
Read 2 more answers
Two lasers are shining on a double slit, with slit separation d. Laser 1 has a wavelength of d/20, whereas laser 2 has a wavelen
Marta_Voda [28]

Answer:

a) that laser 1 has the first interference closer to the central maximum

c) Δy = 0.64 m

Explanation:

The interference phenomenon is described by the expression

         d sin θ = m λ

Where d is the separation of the slits, λ the wavelength and m an integer that indicates the order of interference

For the separation of the lines we use trigonometry

        tan θ = sin θ / cos θ = y / x

In interference experiments the angle is very small

          tan θ = sin θ = y / x

         d y / x = m λ

a) and b) We apply the equation to the first laser

          λ = d / 20

          d y / x = m d / 20

          y = m x / 20

          y = 1 4.80 / 20

          y = 0.24 m

The second laser

        λ = d / 15

          d y / x = m d / 15

          y = m x / 15

          y = 0.32 m

We can see that laser 1 has the first interference closer to the central maximum

c) laser 1

They ask us for the second maximum m = 2

            y₂ = 2 4.8 / 20

            y₂ = 0.48 m

For laser 2 they ask us for the third minimum m = 3

In this case to have a minimum we must add half wavelength

         y₃ = (m + ½) x / 15

         m = 3

         y₃ = (3 + ½) 4.8 / 15

         y₃ = 1.12 m

        Δy = 1.12 - 0.48

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4 0
2 years ago
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ruslelena [56]

Answer:

100nm-280nm

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Ultraviolet rays (UV) are part of the electromagnetic spectrum. It goes from 10nm to 400nm wavelengths, they are shorter than visible light, thus it's impossible to see by a human eye, and larger than X-rays (used in many medical applications and harmful when long-exposed).

According to its wavelengths, UV can be divided in different types:

UVA: long wave UV (315nm-400nm)

UVB: medium-wave UV (280nm-315nm)

UVC: short wave UV (100nm-280nm)

Therefore, UVC comprises wavelengths between 10nm and 280nm.

4 0
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Answer:

a

Explanation:

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