1) See attached figure
The relationship between charge and current is:
where
i is the current
Q is the charge
t is the time
Therefore, the current is the rate of change of the charge passing through a given point over time.
This means that for a graph of charge over time, the current is just equal to the slope of the graph.
For the graph in this problem:
- Between t = 0 and t = 2 s, the slope is

therefore the current is
i = 25 A
- Between t = 2 s and t = 6 s, the slope is

therefore the current is
i = -25 A
- Between t = 6 s and t = 8 s, the slope is

therefore the current is
i = 25 A
The figure attached show these values plotted on a graph.
2)
The previous equation can be rewritten as
This equation is valid if the current is constant: if the current is not constant, then the total charge is simply equal to the area under a current vs time graph.
Here we have the current vs time graph, so we gave to find the area under it.
The area of the first triangle is:

While the area of the second square is

So, the total area (and the total charge) is

The ideal mechanical advantage of a lever (IMA) is given by:

Where:
Le = Effort of the arm
Lr = Resistance arm.
Therefore, we can increase the force adventage by increasing the effort arm or reducing the load arm
Answer:
a. Make the effort length longer.
Answer:
(a) 92 %
(b) 6.76 %
Explanation:
length, l = 4 m, height, h = 5 m, width, w = 3 m, density of water = 1000 kg/m^3
density of ice = 920 kg/m^3, density of mercury = 13600 kg/m^3
(a) Let v be the volume of ice below water surface.
By the principle of flotation
Buoyant force = weight of ice block
Volume immersed x density of water x g = Total volume of ice block x density
of ice x g
v x 1000 x g = V x 920 x g
v / V = 0.92
% of volume immersed in water = v/V x 100 = 0.92 x 100 = 92 %
(b) Let v be the volume of ice below the mercury.
By the principle of flotation
Buoyant force = weight of ice block
Volume immersed x density of mercury x g = Total volume of ice block x
density of ice x g
v x 13600 x g = V x 920 x g
v / V = 0.0676
% of volume immersed in water = v/V x 100 = 0.0676 x 100 = 6.76 %
Answer:
-1786.5J
Explanation:
Temperature 1=T1=25°c
Temperature 2=T2=200°c
Pressure P1=1bar
Pressure P2=0.5bars
T=37°c+273=310k
Note number if moles=1
Recall work done =2.3026RTlogp2/P1
2.3026*8.314*310log(0.5/1)
-1786.5J