Two long parallel guide wires of zero resistance, separated by a distance d=1m, are connected to a potential difference ∆v = 3v. a bar of mass m=5kg and resistance r = 3ω makes contact with these wires, and can slide along them without friction, always remaining perpendicular to the wires. an externally applied uniform magnetic field b=5t is perpendicular to the plane of the bar and the two wires. find the velocity of the bar right after 2 seconds, assuming that the bar has an initial velocity of 1.2 m/s at time t=0.

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray