A metal bar with length L, mass m, and resistance R is placed on a frictionless metal rails that are inclined at an angle phi above the horizontal. The rails have negligible resistance. A uniform magnetic field B is directed downward on the figure (see attachment). The bar is released from rest and slides down the rails.

I already answered all of the following except for part e.

a) Is the direction of the current induced in the bar from a to b, or from b to a?

answer: a to b

b) What is the terminal speed of the bar?

answer: terminal speed = (mg*sin(phi)*R)/(B*L*cos(phi))^2

c) What is the induced current in the bar when the terminal speed has been reached?

answer: induced current = (m*g/B*L)*tan(phi)

d) after the terminal speed has been reached, at what rate is electrical energy being converted to thermal energy?

answer: P = I^2*R = ((m*g/B*L)*tan(phi))^2 * R

e) After the terminal speed has been reached, at what rate is work being done on the bar by gravity?

This one I have no clue how to answer

I thought it would be: W = F*v = mg*((mg*R*sin(phi))/(B*L*cos(phi))^2

but this is not the right answer.

I already answered all of the following except for part e.

a) Is the direction of the current induced in the bar from a to b, or from b to a?

answer: a to b

b) What is the terminal speed of the bar?

answer: terminal speed = (mg*sin(phi)*R)/(B*L*cos(phi))^2

c) What is the induced current in the bar when the terminal speed has been reached?

answer: induced current = (m*g/B*L)*tan(phi)

d) after the terminal speed has been reached, at what rate is electrical energy being converted to thermal energy?

answer: P = I^2*R = ((m*g/B*L)*tan(phi))^2 * R

e) After the terminal speed has been reached, at what rate is work being done on the bar by gravity?

This one I have no clue how to answer

I thought it would be: W = F*v = mg*((mg*R*sin(phi))/(B*L*cos(phi))^2

but this is not the right answer.

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