Answer: 1.39 s
Explanation:
We can solve this problem with the following equations:
(1)
(2)
Where:
is the length the steel wire streches (taking into account 1mm=0.001 m)
is the length of the steel wire before being streched
is the force due gravity (the weight) acting on the pendulum with mass 
is the transversal area of the wire
is the Young modulus for steel
is the period of the pendulum
is the acceleration due gravity
Knowing this, let's begin by finding
:
(3)
Where
is the diameter of the wire
(4)
(5)
Knowing this area we can isolate
from (1):
(6)
And substitute
in (2):
(7)
(8)
Finally:

More protons than electron
The study of science involves the study of the natural world.
Answer: The correct answer is "the speed of the wave becomes four times".
Explanation:
The relation between the speed, frequency and the wavelength is as follows:
v=f\lambda
Here, v is the speed of the wave, f is the frequency and \lambda is the wavelength.
The speed of the sound wave is directly proportional to the frequency.
In the given problem, if the speed of the sound wave is increased four times then the speed of the sound becomes four times.
Therefore, the speed of the sound wave becomes four times.
Answer:
Time taken, 
Explanation:
It is given that, a small metal ball is suspended from the ceiling by a thread of negligible mass. The ball is then set in motion in a horizontal circle so that the thread’s trajectory describes a cone as shown in attached figure.
From the figure,
The sum of forces in y direction is :


Sum of forces in x direction,

.............(1)
Also, 
Equation (1) becomes :

...............(2)
Let t is the time taken for the ball to rotate once around the axis. It is given by :

Put the value of T from equation (2) to the above expression:


On solving above equation :

Hence, this is the required solution.