Answer:
68.8 N
Explanation:
From the question given above, the following data were obtained:
Mass (m) of box = 18 Kg
Coefficient of friction (μ) = 0.39
Force of friction (F) =?
Next, we shall determine the normal force of the box. This is illustrated below:
Mass (m) of object = 18 Kg
Acceleration due to gravity (g) = 9.8 m/s²
Normal force (N) =?
N = mg
N = 18 × 9.8
N = 176.4 N
Finally, we shall determine the force of friction experienced by the object. This is illustrated below:
Coefficient of friction (μ) = 0.39
Normal force (N) = 176.4 N
Force of friction (F) =?
F = μN
F = 0.39 × 176.4
F = 68.796 ≈ 68.8 N
Thus, the box experience a frictional force of 68.8 N.
We will hear the sound of siren of frequency 1553.4606 Hz.
<h3>What is Doppler Effect?</h3>
The apparent change in wave frequency brought on by the movement of a wave source is known as the Doppler effect. When the wave source is coming closer and when it is moving away, the perceived frequency changes. The Doppler effect explains why we hear a passing siren's sound changing in pitch.
according to Dopplers Effect,
![f'=[\frac{v + v_{0} }{v - v_{s} } ]f](https://tex.z-dn.net/?f=f%27%3D%5B%5Cfrac%7Bv%20%2B%20v_%7B0%7D%20%7D%7Bv%20-%20v_%7Bs%7D%20%7D%20%5Df)
![f'= [\frac{700+68.1}{700-94.8} ]* 1224](https://tex.z-dn.net/?f=f%27%3D%20%5B%5Cfrac%7B700%2B68.1%7D%7B700-94.8%7D%20%5D%2A%201224)
the frequency would be 1553.4606 Hz.
to learn more about Doppler Effect go to - brainly.com/question/9165991
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technically usually the warmer object/substances particles move master which causes friction among the particles plus the kinetic energy being converted to thermal energy, so i would say the hand.
If you move a magnet through a loop of wire, induction will happen. The more loops you make, the stronger the effect becomes.
