When a container of water is placed on a laboratory scale, the scale reads 120 g. now a 20-g piece of copper (of density 8.9 g/cm 3) is suspended from a thread and lowered into the water, not touching the bottom of the container. what will the scale now read?
a.122 g b. 140 g c.120 g d.112 g e.138 g

A) 122 g

Explanation:

volume of water displaced

=\frac{20}{8.9}\\

= 2.247 cc

weight of water displaced = 2.247 g wt

upthrust = 2.247 g wt

Reaction of upthrust acting in downward direction = 2.247 g wt

reading of scale = 120 +2.247 = 122.247 g

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d₁ = displacement of tern from arctic to antarctic = 11000 miles

d₂ = displacement of tern from antarctic to arctic =   - 11000 miles

d = total displacement for the journey

total displacement for the journey is given as

d = d₁ + d₂

d = 11000 + (-11000)

d = 0 miles

t₁ = time of travel from arctic to antarctic = 3 months = 3 x 30 days = 90 days

t₂ = time of travel from antarctic to arctic = 3 months = 3 x 30 days = 90 days

t = total time of travel

total time of travel is given as

t = t₁ + t₂

t = 90 + 90

t = 180 days

average velocity is given as

average velocity = total displacement/ total time

v = d/t

v = 0/180

v = 0 miles/day