Why are the orbits of planets only nearly circular and not perfectly circular? PLEASE HELP

What are the similarities & differences between a thermistor and a light dependent resistor in physics?

Along wire carrying a 4.2 a current perpendicular to the xy-plane intersects the x-axis at x=−1.7cm. a second, parallel wire carrying a 3.0 a current intersects the x-axis at x=+1.7cm. part a at what point on the x-axis is the magnetic field zero if the two currents are in the same direction? express your answer to two significant figures and include the appropriate units.

Ais a machine that makes work easier when a single force is applied. a simple machine b compound machine c endangered machine d complex machine