Answer:
The time take is 
Explanation:
From the question we are told that
The decay constant is
The percentage fall is 
The equation for radioactive decay is mathematically represented as

Where is
is the new amount of the new the isotope while
is the original
At initial
% = 1
At
% = 0.80

=> 
=> 
Answer:
Our appliance and electronic energy use calculator allows you to estimate your ... using the formulas provided below; Installing a whole house energy monitoring system. ... energy consumption a few watt-hours, and you can use a monitor to estimate those too. ... Estimate the number of hours per day an appliance runs.
Explanation:
Answer:
118.166 volt
Explanation:
We have given number of turns N =345
Sides of the rectangular coils is 12 cm =0.12 m
So area A =0.12×0.12=0.0144 
Magnetic field B =0.45 T
Angular speed =505 rpm
Speed in rad/sec 
The emf is given by
For maximum emf sinwt =1
So 
If a negative object is used to charge a neutral object, then both objects become charged negatively. In order for the neutral sphere to become negative, it must gain electrons from the negatively charged rod. A metal sphere is electrically neutral. It is touched by a positively charged metal rod.
<h2>
Number of revolutions required to travel 100 yards is 57.</h2>
Explanation:
Diameter of tire,D = 20 inches
Perimeter of tire = πD
Perimeter of tire = π x 20 = 62.8 inches
Distance traveled = 100 yards
1 yard = 36 inches
Distance traveled = 100 x 36 = 3600 inches
In one revolution it travels 62.8 inches.

Number of revolutions required to travel 100 yards is 57.