(Solved): You are conducting an experiment in which a metal bar of length 6.00cm and mass 0.300kg slides ...

You are conducting an experiment in which a metal bar of length $6.00\mathrm{cm}$ and mass $0.300\mathrm{kg}$ slides without friction on two parallel metal rails A resistor with resistance $R=0.800?$ is connected across one end of the rails so that the bar, rails, and resistor form a complete conducting path. The resistances of the rails and of the bar are much less than R and can be ignored. The entire apparatus is in a uniform magnetic field $\vec{B}$ that is directed into the plane of the figure. You give the bar an initial velocity $v=20.0\mathrm{cm}/\mathrm{s}$ to the right and then release it, so that the only force on the bar then is the force exerted by the magnetic field. Using high-speed photography, you measure the magnitude of the acceleration of the bar as a function of its speed. Your results are given in the table: How many seconds does it take the speed of the bar to decrease from $20.0\mathrm{cm}/\mathrm{s}$ to $10.0\mathrm{cm}/\mathrm{s}$ ? Express your answer to three significant figures and include the appropriate units.