Question 6 (5 marks) A DC motor of square coil ABCD with sides 10.0 ch consists of 100 turns. It is rotated in the field of a
uniform permanent magnet of field strength 20 mT, as shown in Figure 5. The current in the square coil
is 500 mA.
Figure 5
In the position shown, what is the magnitude of the net force on the arms AB?
2 marks

In a game of pool, ball a is moving with a velocity v0 of magnitude v0 = 15 ft/s when it strikes balls b and c, which are at rest and aligned as shown. knowing that after the collision the three balls move in the directions indicated and assuming frictionless surfaces and perfectly elastic impact (that is, conservation of energy), determine the magnitudes of the velocities va, vb, and vc.