The electromagnetic waves are types of waves which do not require medium for them to pass through to be able to travel from one location to another. The different types of electromagnetic waves therefore vary only in their wavelength and frequency. Thus, the answer is letter B.
B. The number of field lines on the source charge.
No it will not because F will equal 3 not 0
Potential energy is mass * gravity * height. (m*g*h).
350 = 17*9.8*h <--350 is its energy, 17kg is its mass, and 9.8 is gravity's acceleration on the object. We now just need to solve for h.
h = 350/(17 * 9.8) = 2.1 meters, which, when rounded to the nearest whole meter, is 2 meters.
The shelf is 2 meters high.
D. Speed
"Jorge's Average SPEED is 8km/hr"
hope I helped! also when doing multiple choice try using process of elimination. helps alot :P