we are given in the problem the following dimensions or specifications
B = 0.000055 T r = 0.25 m constant mu0 = 4*pi*10-7
The formula that is applicable from physics is
B = mu0*I/(2*pi*r) I = 2*B*pi*r/mu0 I = 68.75 Amperes
Answer:D
Explanation:
Given
mass of object 
Distance traveled 
velocity acquired 
conserving Energy at the moment when object start falling and when it gains 12 m/s velocity
Initial Energy
Final Energy

where
is friction work if any


Since Friction is Present therefore it is a case of Open system and net external Force is zero
An open system is a system where exchange of energy and mass is allowed and Friction is acting on the object shows that system is Open .
Answer: a) 8.9km/s b) 4.05 x 10^-25 kg
Explanation:
a)
To find the velocity,
V = E/B plug in the numbers we get
V = 1.6kV/m / 0.18 T = 8.9 km/s
b)
To find the ion mass,
m = erB^2/E = 0.125 m x 1.6x10^-19 x (0.18)^2 / ( 1.6 x 10 ^ 3 V/m ) = 4.05 x 10 ^ -25 kg
Heat flows irreversibly from hot to cold
20.3 divided by 3.0 will get u velocity and v times 3.0s