In the circuit shown below, 0.25 A of current flows through a 20-Ω resistor. How much voltage is needed to produce this current? A. 80 V
B. 0.013 V
C. 19.75 V
D. 5 V

On a frictionless air track, a blue glider with mass 0.200 kg is moving to the right with a speed of 8.00 m/s. it strikes a red glider that has mass 0.600 kg and that is initially at rest. after the collision, the blue glider is moving to the left with a speed of 3.00 m/s.(a) what are the magnitude and direction of the velocity of the red glider after the collision? (b) is this collision elastic?