Answer:(a)891.64 N
(b)0.7
Explanation:
Mass of crate 
Crate slows down in 
initial speed 
inclination 
From Work-Energy Principle
Work done by all the Forces is equal to change in Kinetic Energy




change in kinetic energy

(b)Coefficient of sliding friction



and 


<u>Answer:</u>
<h3>During wet and freezing temperatures, ice is able to form at a faster pace on bridges because freezing winds blow from above and below and both sides of the bridge, causing heat to quickly escape. The road freezes slower because it is merely losing heat through its surface.</h3>
<u>Sources:</u>
-- https://intblog.onspot.com/en-us/why-do-bridges-become-icy-before-roads
and
-- https://www.accuweather.com/en/accuweather-ready/why-bridges-freeze-before-roads/687262
I hope this helps you! ^^
Answer:
2.7x10⁻⁸ N/m²
Explanation:
Since the piece of cardboard absorbs totally the light, the radiation pressure can be found using the following equation:

<u>Where:</u>
: is the radiation pressure
I: is the intensity of the light = 8.1 W/m²
c: is the speed of light = 3.00x10⁸ m/s
Hence, the radiation pressure is:

Therefore, the radiation pressure that is produced on the cardboard by the light is 2.7x10⁻⁸ N/m².
I hope it helps you!
Answer:
To calculate the age of a piece of bone
Explanation:
Carbon 14 is an isotope of carbon that is unstable and decays into Nitrogen 14 by emitting an electron. The decay rate of radioactive material is normally expressed in terms of its "half-life" (the time required by half the radioactive nuclei of a sample to undergo radioactive decay). The nice thing about carbon 14 is that its "half-life" is about 5730 years, which gives a nice reference to measure the age of fossils that are some thousand years old.
Carbon 14 dating is used to determine the age of objects that have been living organisms long ago. They measure how much carbon 14 is left in the object after years of decaying without having exchange with the ambient via respiration, ingestion, absorption, etc. and therefore having renewed the normal amount of carbon 14 that is in the ambient.
A rock is not a living organism, so its age cannot be determined by carbon 14 dating.