Several exam questions I got stuck on

[influx]

2) I am unsure why the answer is A.. I thought the answer would be C ( by using flemings left hand rule)

5) If we resolve forces, we get R - mg = mv^2/r , so R = mg + mv^2/r but this isn't the correct answer.. (the correct answer is D)

6) I know when lines of flux are cut, an EMF and therefore a current is induced but how do I get the answer?

thanks

 

[rude man]

2 Use d F = i d L x B on any segment dL around the coil but concentrate on the top, bottom & sides.

5. Consider force on the car due to gravity and force required by centripetal motion. How much does the bridge have to push against the car after you've done that?

6. Apply emf = - d(phi)/dt for all four possibilities. What is the sign of phi on coil X before any action is taken?