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ArbitrLikvidat [17]
3 years ago
15

A child is sledding. He starts at the top of the hill with a velocity of zero, and 3 seconds later he is speeding down the hill

at 12 meters per second. What is the child's acceleration?
Physics
1 answer:
Flauer [41]3 years ago
8 0

Magnitude of acceleration = (change of speed) / (time for the change) =

                                             (12 m/s  -  0)   /   (3 sec)  =

                                               12/3  =  <em>4 m/s²</em>

What's a challenge question ?  Have we all passed the event horizon
and been spaghettified without knowing it ?


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A motorboat maintained a constant speed of 15 miles per hour relative to the water in going 10 miles upstream and then returning
Lesechka [4]

Answer:

speed of current is 5 mile/hr

Explanation:

GIVEN DATA:

speed of motorboat = 15 miles/hr relative with water

let c is speed of current

15-c is speed of boat at  upstream

15+c is speed of boat at downstream

we know that

travel time=distance/speed

\frac{10}{15-c} +\frac{10}{15+c} = 1.5

150+10c+150-10c=1.5(15-c)(15+c)

300=1.5(225-c^2)

300=337.5-1.5c^2

200=225-c^2

c^2=25

c = 5

so speed of current is 5 mile/hr

6 0
3 years ago
A spy camera is said to be able to read the numbers on a car's license plate. If the numbers on the plate are 4.30 cm apart, and
Maslowich

Answer:

D = 2.38 m

Explanation:

This exercise is a diffraction problem where we must be able to separate the license plate numbers, so we must use a criterion to know when two light sources are separated, let's use the Rayleigh criterion, according to this criterion two light sources are separated if The maximum diffraction of a point coincides with the first minimum of the second point, so we can use the diffraction equation for a slit

         a sin θ  = m λ

Where the first minimum occurs for m = 1, as in these experiments the angle is very small, we can approximate the sine to the angle

           θ = λ / a

Also when we use a circular aperture instead of slits, we must use polar coordinates, which introduce a numerical constant

           θ = 1.22 λ / D

Where D is the circular tightness

       

Let's apply this equation to our case

         D = 1.22 λ /  θ

To calculate the angles let's use trigonometry

         tan  θ = y / x

          θ = tan⁻¹  y / x

          θ = tan⁻¹ (4.30 10⁻² / 140 10³)

          θ = tan⁻¹ (3.07 10⁻⁷)

          θ = 3.07 10⁻⁷ rad

Let's calculate

        D = 1.22 600 10⁻⁹ / 3.07 10⁻⁷

        D = 2.38 m

4 0
3 years ago
Read 2 more answers
A golf ball strikes a hard, smooth floor at an angle of 39.8 ° and, as the drawing shows, rebounds at the same angle. The mass o
tangare [24]

Answer:

The magnitude of the impulse is 1.33 kg m/s

Explanation:

please look at the solution in the attached Word file

Download docx
7 0
3 years ago
Read 2 more answers
A loop rests in the plane of a page of textbook while a magnetic field is directed into the page. A clockwise current is induced
Sunny_sXe [5.5K]

Answer:

When the magnetic field is tilted so it is no longer perpendicular to the page.

When the magnetic field gets stronger.

When the size of the loop decreases.

Explanation:

According to the Faraday-Lenz law, the change of the magnetic flux over time causes an induced current, this flux is given by:

\Phi_B=BScos\theta

Therefore, there will be a variable magnetic flux, when the magnitude of the magnetic field (B) changes over time, when the area of the loop (S) changes over time and / or when the angle (\theta) between the field and the surface vector changes over time.

8 0
3 years ago
A laser used to dazzle the audience at a rock concert emits blue light with a wavelength of 463 nm . calculate the frequency of
ZanzabumX [31]

The wavelength of light is given as 463 nm or can also be written as 463 x 10^-9 m. [wavelength = ʎ]

We know that the speed of light is 299 792 458 m / s or approximately 3 x 10^8 m / s. [speed of light = c]

 

Given the two values, we can calculate for the frequence (f) using the formula:

f = c / ʎ

 

Substituting the given values:

f = (3 x 10^8 m / s) / 463 x 10^-9 m

f = 6.48 x 10^14 / s = 6.48 x 10^14 s^-1

<span>f = 6.48 x 10^14 Hz</span>

5 0
3 years ago
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