Answer:
They can't hear an echo in small room because in it the sound can't be reflected back. For an echo of a sound to be heard,the minimum distance between the source of sound and the walls of the room should be 17.2 m.
hopw it helps
-- The acceleration of gravity is 9.8 m/s².
So if there's no air resistance, the speed of a falling object
always increases by 9.8 m/s for every second it falls.
Speed = (original speed) + (gravity x falling time)
-- If it has no vertical speed when it started, then at the end
of 3 seconds, its speed is
= (0) + (9.8 m/s² x 3 sec)
Velocity = 29.4 m/s downward .
Explanation:
<em>The height of the pendulum is measured from the lowest point it reaches (point 3). </em>
At 1, the kinetic energy of the pendulum is zero (because it is not moving), and it has maximum potential energy.
At 2, the pendulum has both kinetic and potential energy, and how much of each it has depends on its height—smaller the height greater the kinetic energy and lower the potential energy.
At 3, the height is zero; therefore, the pendulum has no potential energy, and has maximum kinetic energy.
At 4, the pendulum again gains potential energy as it climbs back up, Again how much of each forms of energy it has depends on its height.
At 5, the maximum height is reached again; therefore, the pendulum has maximum potential energy and no kinetic energy.
Hope this helps :)
Answer:
Thus the time taken is calculated as 387.69 years
Solution:
As per the question:
Half life of 
= 28.5 yrs
Now,
To calculate the time, t in which the 99.99% of the release in the reactor:
By using the formula:
where
N = No. of nuclei left after time t
= No. of nuclei initially started with
(Since, 100% - 99.99% = 0.01%)
Thus
Taking log on both the sides:
t = 387.69 yrs
