<span> d = r*t is the basic distance equation
d = 6000 km
t with the tail wind = 6 hr
r with the tail wind = speed of the plane + wind speed = s + w
t with the head wind = 7.5 hr
r with the head wind = speed of the plane - wind speed = s-w
(s+w)*6 = 6000
(s-w)*7.5 = 6000
s + w = 1000
s - w = 800
</span><span> 2s = 1800
s = 900 km/h
s + w = 1000
w = 100
Check the anwer by calculating the return trip.
(900-100) * 7.5 = 800 * 7.5
800 * 7.5 = 6000 km
Answer: The rate of the jet in still air is 900 km/h. The rate of the wind is 100 km/hr.</span>
The mass on the spring is 0.86 kg
Explanation:
The period of a mass-spring system is given by the equation

where
m is the mass
k is the spring constant
In this problem, we have:
k = 88.7 N/m is the spring constant
The system makes 15 oscillations in 9.24 s: therefore, the period of the system is

Now we can re-arrange the first equation to solve for the mass:

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Explanation:
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<span>Each atom contains an equal number of protons and electrons; these particles will be equal in value to an element's atomic number</span>
Answer:
3 fans per 15 A circuit
Explanation:
From the question and the data given, the light load let fan would have been
(60 * 4)/120 = 240/120 = 2 A.
Next, we add the current of the fan motor to it, so,
2 A + 1.8 A = 3.8 A.
Since the devices are continuos duty and the circuit current must be limited to 80%, then the Breaker load max would be
0.8 * 15 A = 12 A.
Now, we can get the number if fans, which will be
12 A/ 3.8 A = 3.16 fans, or approximately, 3 fans per 15 A circuit.