Answer:
Q' = 115.2 KJ
Explanation:
Given that
Current I = 10 A
Voltage = 120 V
Time t= 120 s
The energy supplied Q= V I t
Q= 10 x 120 x 120 J
Q= 144 x 1000 J
Q= 144 KJ
The change in the energy ΔEngg = 28.8 kJ
By using energy conservation
Q= Q' + ΔEngg
Q'=Wasted energy
Now by putting the values in the above equation
144 = Q' + 28.8 KJ
Q' = 115.2 KJ
Therefore the waste energy will be 115 kJ.
It can be said that most of the required information's are already given in the question.
Let us assume the speed of the passenger train = x
Speed of the freight train = y
x = y + 40
The second equation will be
6 * x = 10 * y
6x = 10y
Dividing both sides by 2, we get
3x = 5y
x = 5y/3
Putting the value of "x" in the first equation, we get
x = y + 40
5y/3 = y + 40
5y = 3y + 120
5y - 3y = 120
2y = 120
y = 60 mph
Putting the value of y in the first equation, we get
x = y + 40
= 60 + 40
= 100 mph
From the above deduction, we can conclude that the passenger train is traveling at 100 mph and the freight train is traveling at 60 mph.
At a definite point, the bridge would begin oscillating to the matching rhythm as that
of the marching footsteps.
This oscillation would touch a determined peak when the bridge can
no longer tolerate its own
power and later collapses. So, soldiers are
systematic to break their steps
while passing a bridge.
