For these two questions, first you need to know that the voltage across each branch of a parallel circuit is the same.
So, for Q5, we can first find out the voltage across R₂ by V=IR.
Voltage across R₂ = 2.5 × 8 = 20V
Since R₂ and R₃ are in parallel circuit, their voltage should be the same. Thus, voltage across R₃ is 20V.
So, by V=IR,
current of R₃ = 
= 5A
Q6. voltage across R₁ = 2 × 4 = 8V
∴voltage across R₂ = 8V
current of R₂ = 
= 1A
<h3><u>Alternative method</u></h3>
From these two examples, you can find out that the current of each branch of the parallel circuit is inversely proportional to the resistance of the branch.
ie. for Q5,
= 
= 
I₃ = 5A
Q6. 
= 
= 
I₂ = 1A
Answer:
The current in the circuit must be zero.
Explanation:
In a RC circuit, the steady state is reached when either the capacitor is fully charged or fully discharged. In either case, there must not be any current through the circuit because if it exists, it will deliver charge to the capacitor and thus change its charge, which is not a steady state.
Answer:
0.001 s
Explanation:
The force applied on an object is equal to the rate of change of momentum of the object:
where
F is the force applied
is the change in momentum
is the time interval
The change in momentum can be written as
where
m is the mass
v is the final velocity
u is the initial velocity
So the original equation can be written as
In this problem:
m = 5 kg is the mass of the fist
u = 9 m/s is the initial velocity
v = 0 is the final velocity
F = -45,000 N is the force applied (negative because its direction is opposite to the motion)
Therefore, we can re-arrange the equation to solve for the time:
I think it is A. but then you can also produce your own energy
Speed = distance / time
S= 40 000m / 5400s
S= 7.41m/s
