How many million Christmas trees were sold in the year 2000?
1 answer:
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Answer:
x = 240 m
Explanation:
This is a kinematics exercise
Let's fix our frame of reference on car A
x = x₀ₐ+ v₀ₐ t + ½ aₐ t²
the initial position of car a is zero
x = 0 + v₀ₐ t + ½ 0.8 t²
for car B
x = x_{ob} + v_{ob} t - ½ a_b t²
car B's starting position is 30 m
x = 30 + v_{ob} t - ½ 0.4 t²
at the point where they meet, the position of the two vehicles is the same
0 + v₀ₐ t + ½ 0.8 t² = 30 + v_{ob} t - ½ 0.4 t²
let's reduce the speeds to the SI system
v₀ₐ = 14.4 km / h (1000 m / 1 km) (1h / 3600s) = 4 m / s
v_{ob} = 23.4 km / h = 6.5 m / s
4 t + 0.4 t² = 30 + 6.5 t - 0.2 t²
0.2 t² - 2.5 t - 30 = 0
t² - 12.5 t - 150 = 0
we solve the quadratic equation
t =
t =
t₁ = 20 s
t₂ = -7.5 s
time must be a positive quantity so the correct result is t = 20 s
let's look for the distance
x = 4 t + ½ 0.8 t²
x = 4 20 + ½ 0.8 20²
x = 240 m
To solve this problem it is necessary to take into account the concepts related to frequency and period, and how they are related to each other.
The relationship that defines both agreements is given by the equation,
Then the frequency for the previous period given (2sec) is
The beat frequency of two frequencies is equal to the difference between the two frequencies, then
<em>Hence option A is incorrect.</em>
We can do this process for 254Hz as and 258 Hz for
, then
<em>Hence option B is incorrect. </em>
We can also do this process for 255Hz as and 257 Hz for
, then
<em>Hence option C is incorrect. </em>
We can also do this process for 255.5Hz as f_1 and 256.5 Hz for f_2, then
<em>Hence option D is incorrect. </em>
We can also do this process for 255.75Hz as and 256.25 Hz for
, then
<em>Hence option E is incorrect. </em>
Therefore the sum of the frequencies in the sound wave would be 256.25Hz and 255.75Hz