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Crank
4 years ago
15

While you are driving down a country road at dusk with a velocity of 22 m/s, a deer suddenly runs across the road in front of yo

u. You apply the brakes, reducing your velocity to 7 m/s in 5 s as you avoid hitting the deer. What is the acceleration of the car?
Physics
1 answer:
juin [17]4 years ago
7 0

Answer:

a=\frac{v_{f}-v_{o}  }{t_{f}-t_{o}  } =\frac{(7-22)\frac{m}{s} }{5s-0s} =-3\frac{m}{s^{2} }

Explanation:

We know that the initial velocity is 22 m/s

<u>The final velocity </u><u>after applying the brakes</u><u> is 7 m/s, and the time that takes it to break is </u><u>5 seconds</u>

We know that the concept of acceleration is the change of velocity in time

a=\frac{v_{f}-v_{o}  }{t_{f}-t_{o}  } =\frac{(7-22)\frac{m}{s} }{5s-0s} =-3\frac{m}{s^{2} }

<u><em>The answer is negative since the car is slowing down  </em></u>

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A unit of time sometimes used in microscopic physics is the "shake". One shake equals 10−8 s.
Lady_Fox [76]

Answer:

(a) There are 3.17 times more shakes in a second than seconds in a year.

(b) Humans have existed for 9067.72 universe seconds.

Explanation:

(a) First we calcule how many seconds are in a year. One year have 365 days, one day has 24 hours, one hour has 60 minutes and one minute has 60 seconds, so:

60s*60*24*365=3.1536*10^7s

Now, we calculate how many shakes are in a second:

1s*\frac{1shake}{10^{-8}s}=10^8shakes

Finally, we calculate how many more shakes in a second are there than seconds in a year:

\frac{10^8s}{3.1536*10^7s}=3.17

(b) Using a simple rule of three we can calculate  how many "universe seconds" have humans existed, recall that 1 day has 86400 seconds:

1010 years--------->86400s

106 years----------> x seconds

x=\frac{106y*86400s}{1010y}=9067.72s

3 0
3 years ago
a stone is dropped from a bridge and hits the pavement below in 2 seconds. what is the velocity of the stone when it hits the pa
ira [324]
Well gravity is 9.8m/s so i would assume 19.6m/2 is the velocity
8 0
3 years ago
Read 2 more answers
Find the minimum value of n in the Balmer series for which the predicted wavelength is in the ultraviolet region of the spectrum
d1i1m1o1n [39]

Answer:

 λ =365.4 nm

Explanation:

Boh's atomic model of the Hydrogen atom the energy of each level is

        Eₙ = - 13.606 / n²

where the synergy is in electonvotes and the value of E₀ = 13.606 eV is the energy of the base state of hydrogen.

An atomic transition occurs when an electron goes from an excited state and joins everything of lower energy.

                 ED = 13.606 (1 / n₀² - 1 /n_{f}^{2})

we are going to apply this relationship to answer slash.

 

At the beginning of the studies of atomic transitions, each group did not consider having a different name

name        Initial state

Lymman         1

Balmer           2

the final state is any other state sta the continuum that corresponds to n = inf

Let's look for the highest energy of the Balmer series

              ΔE = 13.606 (1/2² - 1 /∞)

              ΔE = 3.4015 eV

Let's use the Planck relation for the energy

                E = h f = h c /λ

                λ = h c / E

Let's reduce the energy to J

              E = 3.4015 eV (1.6 10⁻¹⁹ J / 1 eV) = 5.4424 10⁻¹⁹

            λ = 6.63 10⁻³⁴  3 10⁸ / 5.4424 10⁻¹⁹

            λ = 3.654 10⁻⁷ m

            λ = 3,654 10⁻⁷ m (10⁹ nm / 1m)

            λ =365.4 nm

this eta radiation in the ultraviolet range

5 0
3 years ago
Nikolas had an idea that he could use the compressed carbon dioxide in a fire extinguisher to propel him on his skateboard.
Vikentia [17]
The Newton’s law Nikolas would use to come up with this idea is the <span>Third law that states:

</span><span>When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
</span>
So, in this case, let's name the first Body A which is the skateboard and the second body B which is <span>the compressed carbon dioxide in a fire extinguisher. Then, as shown in the figure below, according to the Third law:

</span>FA = -FB<span>

</span>

8 0
3 years ago
Read 2 more answers
When the point of reference (the observer) is in motion, it flips the "rules" of vector addition (you ADD the vectors going in o
KengaRu [80]

Answer:

the statement is TRUE

Explanation:

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When the two vehicles go in opposite directions, the speed is much higher, so we must add their speeds

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     v_relative = v₁ + v₂

therefore the statement is TRUE

3 0
3 years ago
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