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:
Answer:
A
Explanation: A is a example of Air resistance force, which is a contact force.
Wee can use here kinematics
as we know that

for shorter tree we know that


now since we know that other tree is twice high
So height of other tree is y = 39.2 m
now again by above equation



so the time taken is 2.83 s
Answer:
1 ohm
Explanation:
since there are two identical resistors, one resistor will be
R =
=2ohm [ proven as in series
]
to calculate the equivalent resistance when in parallel:

so,


Frictional force and Applied force has same “magnitude” and “opposite” direction.
Option: B
<u>Explanation</u>:
When a book is moved horizontally by applying “force” on the book, the frictional force is opposed to the book by the table. Here, this “frictional force” is opposing the book has the same force what we applied on the book but this frictional force and the applied force are opposite in direction. Always the “frictional force” is opposite to the “applied force” which stops the object to move. For example, if a force applied leftward to the object the frictional force is acted on the right side of the object.
When two objects are in contact they experience a "frictional force". This "frictional force" acts opposite to the force applied on to move the object.
Formula for "frictional force" is 
Where,
is coefficient of friction and N is normal force.