Two groups of students are doing controlled experiments with electromagnets. They each start with an electromagnet that has 30 winds on the core, one D-cell, and a switch. All of the equipment that the groups are using is the same. Group 1 decides to improve the electromagnet design by changing the number of D-cells in the circuit. They will test 2 D-cells to see if performance is improved. Group 2 decides to improve the electromagnet design by adding 20 more winds and doubling the thickness of the wire used. 5. Which group has a better experimental design? Why do you think so?

need to see circuit to get time constant

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.

russian is not my first language, so i'm afraid i can't write out an answer in russian, but hopefully you can find a way to do so. here's my best translation of the problem: you're given a plot of a particle's position in one-dimensional space over time, and you're asked to find either the total distance traveled by the particle after 6 seconds had elapsed, or the total displacement of the particle after 6 seconds.

if you want the total distance traveled, you would first need to determine the particle's velocity as a function of time, then integrate that over the 6-second interval. we know the position function is quadratic with roots at 0 and 6, so we have

where is unknown. because the position is parabolic, there is symmetry about the midpoint at , and we know that

so that the position function is

which means the velocity is

then the total distance traveled is

so the total distance traveled is 20 m.

on the other hand, if you want to find displacement: the particle starts at and ends at , so its displacement is 0.