The average dissipated power in a resistor in a ac circuit is:

where R is the resistance, and

is the root mean square current, defined as

where

is the peak value of the current. Substituting the second formula into the first one, we find

and if we re-arrange this formula and use the data of the problem, we can find the value of the peak current I0:
Given:-
- Speed of the unicycle = 20 m/s
- Time taken = 15 s
To Find: Distance travelled by the unicycle.
We know,
s = vt
where,
- s = Distance travelled,
- v = Speed &
- t = Time taken.
Therefore,
s = (20 m/s)(15 s)
→ s = (20 m)(15)
→ s = 300 m (Ans.)
-- The net force on the box is 2N to the left.
-- The box will move to the left and accelerate to the left.
-- F=ma . a=F/m . a=(2N)/(4kg).
a = 0.5 m/s^2 to the left.
Ideally, 576 J because energy is conserved.
In the real world, a tiny tiny tiny tiny bit less than 576 J ,
because we live in a world with friction and air resistance.
Answer:
A) 
B) 
C) 
D) mosquitoes speed in part B is very much larger than that of part C.
Explanation:
Given:
- Distance form the sound source,

- sound intensity level at the given location,

- diameter of the eardrum membrane in humans,

- We have the minimum detectable intensity to the human ears,

(A)
<u>Now the intensity of the sound at the given location is related mathematically as:</u>
..........................................(1)



<em>As we know :</em>


is the energy transferred to the eardrums per second.
(B)
mass of mosquito, 
<u>Now the velocity of mosquito for the same kinetic energy:</u>



(C)
Given:
- Sound intensity,

<u>Using eq. (1)</u>



Now, power:



Hence:




(D)
mosquitoes speed in part B is very much larger than that of part C.