Answer:
(a) the initially stationary spelunker is accelerated to a speed of 4.70 m/s - 6106 J
(b) he is then lifted at the constant speed of 4.70 m/s - 5488 J
(c) finally he is decelerated to zero speed. How much work is done on the 56.0 kg rescue by the force lifting him during each stage - 4869 J
Explanation:
knowing
d = 10 m
m = 56 kg
The work done by the applied force to pull the spelunker is given by
Wa + Wg = Kf - Ki
Wg = -mgd
First
Wa = mgd + 0.5 - 0.5
Wa = (56*9.8*10) + (0.5*56*)
Wa = 6106 J
Second
Kf = Ki
Wa = mgd + 0.5 - 0.5
Wa = 56*9.8*10
Wa = 5488 J
Third
Kf = 0
Wa = mgd + 0.5 - 0.5
Wa = (56*9.8*10) - (0.5*56*)
Wa = 4869 J
Given that,
Distance, d = 10700 km
Time taken by the airplane to complete the destination, t = 12 hours
We need to find the speed of the airplane. It is equal to the total distance covered divided by total time taken. So,
We know that,
1 km = 1000 m
1 h = 3600 s
So,
So, the speed of the airplane is 891.66 km/h or 247.68 m/s.
Answer:
<em>a. all three resistors in parallel</em>
Explanation:
<u>Combination of Resistors</u>
The power supplied by a power source or V volts is:
where R is the equivalent resistance of the whole circuit connected to the power source.
As shown, the power is inversely proportional to R which means that if R is a minimum, P is a maximum.
The problem reduces now to find the combination of resistors that produces the least value of its equivalent. If three resistors are connected in series, the equivalent is the sum of all them
This equation gives R a value that is greater than the greatest of all three resistances.
If they are connected in parallel, the equivalent is given by
This equation produces for R a value that is smaller than the smallest value from the three resistances.
Any other combination of resistors will produce intermediate values between the maximum (series) and the minimum (parallel), thus:
a. all three resistors in parallel
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