The best answer is b - span.
A span is the distance between two bridge supports The supports may be towers, columns, or even the wall of a canyon.
There are many kinds of bridges but they all fall into three types namely beam, arch and suspension. The major difference between these three kinds of bridges is the distance that each can cross in a single span.
For example, a modern beam bridge is likely to span a distance of 200 feet, a modern arch can span 800 or 1000feet, and a modern suspension bridge can span up to 7000ft.
Electrostatic forces are non-contact forces; they pull or push on objects without touching them
Answer:
dP/dt = 26.12 W/s
Explanation:
First, we need to find the value of dt at the instant when R₃ becomes 91.7 Ω. Therefore, we use:
dR₃/dt = 0.552 Ω/s
where,
dR₃ = Change in value of resistance 3 = 91.7 Ω - 7.42 Ω = 84.28 Ω
dt = time interval = ?
Therefore,
84.28 Ω = (0.552 Ω/s)(dt)
dt = (84.28 Ω)/(0.552 Ω/s)
dt = 152.68 s
Now, we find change in power (dP):
dP = V(R₁ + R₂ + dR₃)
dP = (42.1 V)(2.96 Ω + 7.48 Ω + 84.28 Ω)
dP = 3987.71 W
Dividing by dt:
dP/dt = 3987.71 W/152.68 s
<u>dP/dt = 26.12 W/s</u>
Question:
Calculate the change in internal energy of the following system: A balloon is cooled by removing 0.652 kJ of heat. It shrinks on cooling, and the atmosphere does 389 J of work on the balloon. Express your answer in Joules (J)
Answer:
-263J
Explanation:
Though its difficult and infact impossible to measure the internal energy of a system, the change in internal energy ΔE, can however be determined. This change when it is accompanied by work(W) and transfer of heat(Q) in or out of the system, can be calculated as follows;
ΔE = Q + W ----------------(i)
Q is negative if heat is lost. It is positive otherwise
W is negative if work is done by the system. It is positive otherwise.
From the question;
Q = -0.652kJ = -652J {the negative sign shows heat loss}
W = +389J {the positive sign shows work done on the system(balloon)}
<em>Substitute these values into equation (i) as follows;</em>
ΔE = -652 + 389
ΔE = -263J
Therefore the change in internal energy is -263J
PS: The negative sign shows that the process is exothermic. This means that the system (balloon) lost some energy to the environment.