What is the efficiency when 5j is supplied to a buzzer and 2j is transferred into sound energy?

40%

Explanation:

The efficiency of a system is calculated as the ratio of the useful power output to that of the input power.

Efficiency = useful output/input x 100%

In this case, input power = 5j, useful output = 2j

Efficiency = 2/5 x 100%

                   = 40%

The efficiency of the buzzer is, therefore, 40%.

1/0.14nm = 10^10/1.4 a lot

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