when a flower petal is 4.0 cm in front of a converging lens, the inverted image is half the height of the petal. what is the focal length of this lens?

Asimply means that over time there was some sort of change.

James is trying to prove newton's 2nd law of motion. he tries to move four different objects with different masses, shapes, and sizes from point a to point b. the objects are a toy car, a car, a refrigerator, and a kitchen table. after some experimentation, he finds that force is dependent on the mass of the object, rather than it's size or shape. the object that takes the most force to move is the

Explain why electric current cannot exist if a current doesn't have a voltage source.