Answer:
Explanation:
Hello! To solve this problem we must be clear about the concept of energy conservation, and kinetic energy with the following sentence
The kinetic energy of the two cars (v = 1.2m / S) plus the kinetic energy of the third car (v = 3.5m / S) must be equal to the kinetic energy of the three cars together.
The kinetic energy is calculated by the following equation.
m= mass of the cars=26500kg
V=speed
E=kinetic energy
taking into account the above, the following equation is inferred
1= the cars are separated
2=
the cars are togheter
E1=E2
where
m= mass of each car
V1= 1.2m/s
Va=3.5,m/S
m= mass of each car
V=speed (in m/s) of the three coupled cars after the first couples with the other two
Solving
the speed of the three coupled cars after the first couples with the other two is 2.245m/s
Answer:
(a) the observed frequency is 200 Hz
(b) the observed frequency is 188 Hz.
Explanation:
speed of the truck, Vs = 27 m/s
frequency of the truck as it approaches, Fs = 185 Hz
(a) Apply Doppler effect to determine the frequency you will hear.
As the truck approaches you, the observed frequency will be higher than the source frequency because of decrease in distance.
![F_s = F_o [\frac{V}{V_S + V} ]](https://tex.z-dn.net/?f=F_s%20%3D%20F_o%20%5B%5Cfrac%7BV%7D%7BV_S%20%2B%20V%7D%20%5D)
Where;
Fo is the observed frequency which is the frequency you will hear.
V is speed of sound in air
![F_s = F_o [\frac{V}{V_S + V} ]\\\\185 = F_o [\frac{340}{27 + 340} ]\\\\185 = F_o (0.926)\\\\F_o = \frac{185}{0.926}\\\\F_o = 199.78 \ Hz](https://tex.z-dn.net/?f=F_s%20%3D%20F_o%20%5B%5Cfrac%7BV%7D%7BV_S%20%2B%20V%7D%20%5D%5C%5C%5C%5C185%20%3D%20F_o%20%5B%5Cfrac%7B340%7D%7B27%20%2B%20340%7D%20%5D%5C%5C%5C%5C185%20%3D%20F_o%20%280.926%29%5C%5C%5C%5CF_o%20%3D%20%5Cfrac%7B185%7D%7B0.926%7D%5C%5C%5C%5CF_o%20%3D%20199.78%20%5C%20Hz)
(b) Apply the following formula for a moving observer and a moving source;
](https://tex.z-dn.net/?f=F_o%20%3D%20F_s%5B%5Cfrac%7BV-V_o%7D%7BV%7D%20%5D%28%5Cfrac%7BV%7D%7BV-V_S%7D%20%29)
The observed frequency is negative since you are driving away from the truck and the source frequency is also negative since it is driving towards you.
\\\\F_o = 185[\frac{340-22}{340} ](\frac{340}{340-27} )\\\\F_o = 185(0.9353)(1.0863)\\\\F_o = 188 \ Hz](https://tex.z-dn.net/?f=F_o%20%3D%20F_s%5B%5Cfrac%7BV-V_o%7D%7BV%7D%20%5D%28%5Cfrac%7BV%7D%7BV-V_S%7D%20%29%5C%5C%5C%5CF_o%20%3D%20185%5B%5Cfrac%7B340-22%7D%7B340%7D%20%5D%28%5Cfrac%7B340%7D%7B340-27%7D%20%29%5C%5C%5C%5CF_o%20%3D%20185%280.9353%29%281.0863%29%5C%5C%5C%5CF_o%20%3D%20188%20%5C%20Hz)
Answer:
w = w₀ M / (M + 2m)
Explanation:
This exercise can be solved using the concepts of conservation of angular momentum
L = I w
Let's write in angular momentum in two points
Initial. Before impact
L₀ = I w₀
Final. After the rock has stuck
= I w + (m r²) w
The system is formed by the disk and the rock, so that the forces and moments during the crash are internal and the angular momentum is preserved
L₀ =
I w₀ = (I + m r²) w
w = w₀ I / (I + m r²)
The roundabout is a disk so its moment of inertia is
I = ½ M r²
w = w₀ ½ Mr² / (½ M r² + mr²)
w = w₀ ½ M / (½ M + m)
w = w₀ ½ M2 / (M + 2m)
w = w₀ M / (M + 2m)
Yes, you need to convert unless the question specifically requires km/h.
Answer:
B: Relay
Explanation:
Out of all the options, the only device that relies upon the magnetic field of an electric current.
The principle relies upon the principle of electro magnetic attraction whereby when the circuit detects a faulty current, it makes the electromagnetic field to become energized which in turn produces the temporary magnetic field. This magnetic field then moves the relay armature which is used in opening or closing the connections.
