An astronaut whose mass is 80. kg carries an empty oxygen tank with a mass of 10. kg. the astronaut throws the tank away with a speed of 2.0 m/s. with what velocity does the astronaut start to move off into space?

v' = -0.25 m/s

Explanation:

given,

mass of the astronaut,M = 80 kg

mass of the oxygen tank, m= 10 Kg

speed at which tank is thrown, v= 2 m/s

using conservation of momentum

( M+ m ) u = M v' + m v

initial velocity of the system is zero

     0 = 80 x v' + 10 x 2

     v' =

     v' = -0.25 m/s

negative sign represent that the speed of the astronaut is in opposite direction to motion of cylinder.

Speed of the astronaut is equal to 0.25 m/s

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

d.7.5cm is your answer