Answer:t=0.81 s
Explanation:
Given
Penguin slides down with constant velocity of 3.57 m/s
as the Penguin Slides with constant velocity therefore
is zero on Penguin

friction Force

coefficient of Kinetic friction



after reaching on floor final velocity of penguin will be zero after time t
thus

here 
(deceleration)



<h2>
Answer: Prism</h2>
In the eighteenth century Isaac Newton found out that <u>when a beam of light from the Sun, passes trhough a prism is decomposed in many different colors</u>. He named this phenomenom as dispersion of light.
This phenomenom occurs when a beam of white light (which is compound of many wavelengths or "colors") is refracted (the different rays of light are diverted depending on their wavelengths) in some medium, leaving their constituent colors separated.
Therefore:
<h2>Isaac Newton used a <u>prism</u> to break white light into its component colors.</h2>
B) millimeter, centimeter, meter, kilometer
Answer:
Here we need to make parallel connection of two 80 ohm resistors to achieve 40 ohm net resistance.
Explanation:
As we know that the resistances in series add up directly and here we are given with only the resistors of 80 Ω.
So when we connect two resistors of 80 ohm in parallel we get the resultant of 40 ohm.
Mathematically:



gives us the only combination of two resistors in parallel.
Mass = 1.2 kg = 1200 grams.
Volume = mass/density = 1200 cm3.
Hope this helps!