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:
Although the Earth has a lesser mass than the Sun, it is far closer to you, allowing for a stronger pull.
Explanation:
Answer:
3 volts
Explanation:
Number of turns in primary coil =
= 100
Number of turns in secondary coil =
= 200
Voltage across primary coil =
= 1.5 volts
Voltage across secondary coil =
= ?
In a transformer, the ratio of number of turns of primary to secondary coil is equal to the ratio of the respective voltages i.e.

Using the given values, we get:

Thus, the voltage measure across secondary coil would be 3 volts
Answer:
39.240 W
Explanation:
Let's start by calculating the work done by the engine. We can assume that it is the same work done by the weight of the object to bring it from 40m to the surface: as much energy it takes to bring it up, the same ammount it takes to bring it down. Said work is 
At this point we can simply apply the definition of power, that is
, to get the power of the engine is 
I am assuming you know the relation obtained between slit width, distance of screen from slits, distance of interference pattern obtained on the screen from the center and the wavelength of monochromatic light used in Young's Double Slit experiment.
λ =

λ ~ 1.97 ×10⁻⁷m