Two masses 5 and 7 kg are originally at rest on a frictionless surface. the masses are connected by a light cord. a second cord is attached to the 7 kg mass and pulled with a horizontal force of 30 n such that the masses accelerate in a single direction. what is the tension in the cord that connects the two masses?

12.5 N

Explanation:

We can find out about the tension of the cord pulling the 5kg mass by first calculate the horizontal acceleration of said mass, which is the same as the horizontal acceleration of the whole system.

Total system mass M = 5 + 7 = 12 kg

Total system acceleration = F/M = 30/12 = 2.5 (m/s2)

The tension force acting on the 5kg mass in order to exert a 2.5 m/s2 acceleration is

f = ma = 5*2.5 = 12.5 N

answer: the answer is a

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