Answer:
Square
Step-by-step explanation:
square - (geometry) a plane rectangle with four equal sides and four right angles
When the velocity goes from 40km/h to 20 km/h, the kinetic energy decreases by a factor of 4.
<h3>
What happens to the kinetic energy?</h3>
We know that the kinetic energy depends of the square of the velocity. Thus, if we decrease the velocity from 40km/h to 20km/h, then the kinetic energy decreases.
Remember that the kinetic energy is:
K = (m/2)*v²
Where m is the mass.
The initial kinetic energy is:
K = (m/2)*(40km/h)²
The final kinetic energy is:
K' = (m/2)*(20km/h)²
The quotient gives:
K/K' = [ (m/2)*(40km/h)²]/[ (m/2)*(20km/h)²]
K/K' = (40km/h)²/(20km/h)² = 4
So the kinetic energy decreases by a factor of 4.
Learn more about kinetic energy:
brainly.com/question/25959744
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Answer:
- ![\frac{\sqrt{2+\sqrt{3} } }{2}](https://tex.z-dn.net/?f=%5Cfrac%7B%5Csqrt%7B2%2B%5Csqrt%7B3%7D%20%7D%20%7D%7B2%7D)
Step-by-step explanation:
using the half angle formula
cos(
) = ± ![\sqrt{\frac{1+cosx}{2} }](https://tex.z-dn.net/?f=%5Csqrt%7B%5Cfrac%7B1%2Bcosx%7D%7B2%7D%20%7D)
cos195° = cos(180 + 15)° = - cos15°
then
cos15° = cos (
) =
=
=
= ![\frac{\sqrt{2+\sqrt{3} } }{2}](https://tex.z-dn.net/?f=%5Cfrac%7B%5Csqrt%7B2%2B%5Csqrt%7B3%7D%20%7D%20%7D%7B2%7D)
then
cos195° = - cos15° = - ![\frac{\sqrt{2+\sqrt{3} } }{2}](https://tex.z-dn.net/?f=%5Cfrac%7B%5Csqrt%7B2%2B%5Csqrt%7B3%7D%20%7D%20%7D%7B2%7D)