A \"rail gun\" is a device wherein a payload is accelerated along a rail via ele

Question

A "rail gun" is a device wherein a payload is accelerated along a rail via electromagnetic forces. Schematically, it looks like this: Assume the bar has resistance R and mass m and sits on a frictionless perfectly conducting U-shaped wire track which is connected to a voltage source as shown in the figure above. The width between the two arms of the track is w. When the switch is closed the bar is observed to immediately accelerate to the right with an initial acceleration of a_0. Assume that the entire track is embedded in a uniform vertical magnetic field. Part (a): What is the orientation and strength of the uniform magnetic field? Explain how you know this. Part (b): In fact, the acceleration is not constant and after some time the acceleration drops and eventually the bar is moving at constant speed and will go no faster. What is the value of v_max, the maximum speed of the bar in terms of the parameters given? Explain your work.

Explanation / Answer

a) here the bar is accelarationg due to magnetic force ,the direction of force is along the direction of accelaration i.e F = m*a

F = m*ao = magnetic force = B*i*w

current induced is i = Vo/R

then m*ao = B*Vo*w/R

B = m*ao*R/(Vo*w)

orientation is vertically downwards

b) Vo = B*w*v_max

v_max = Vo/(B*w)

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.