Answer:
The force due to friction is generally independent of the contact area between the two surfaces. This means that even if you have two heavy objects of the same mass, where one is half as long and twice as high as the other one, they still experience the same frictional force when you drag them over the ground.
Explanation:
Independent
The correct option is (B) <span>Aluminum is a metal and is shiny, malleable, ductile, conducts heat and electricity, forms basic oxides, and forms cations in aqueous solution.
Since Aluminium is in group 13, and all the elements in group 13 are either metals or metalloids(Boron). Hence we are left with option (B) and (D). Boron is the only metalloid in group 13 and aluminium is a metal(not a metalloid); therefore, we are left with only one option which is Option (B). And Aluminium is </span>shiny, malleable, ductile, conducts heat and electricity, forms basic oxides, and forms cations in aqueous solution.<span>
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Answer:
r₂ = 0.2 m
Explanation:
given,
distance = 20 m
sound of average whisper = 30 dB
distance moved closer = ?
new frequency = 80 dB
using formula

I₀ = 10⁻¹² W/m²
now,



to hear the whisper sound = 80 dB



we know intensity of sound is inversely proportional to square of distances



r₂ = 0.2 m
Answer:
Density of 18.0-karat gold mixture is
.
Explanation:
A mixture of 18 parts gold, 5 parts silver, and 1 part copper.
Let mass of gold be 18x
Let the mass of silver be 5x
Let the mass of copper be 1x
The density of gold = 
The density of silver = 
The density of copper =

Volume of the gold in the mixture = 
Volume of the silver in the mixture = 
Volume of the copper in the mixture = 
Mass of the mixture = M = 18x+5x+1x =24x
Volume of the mixture = 
Density of the mixture:
