Два точкові заряди 7·10^-9 і 14·10^-9 Кл знаходяться на відстані 0,4 м. Яку роботу потрібно здійснити, щоб зблизити їх до відстані 0,25 м? Помогите пожалуйста

Light from a sodium lamp passes through a diffraction grating that has 1000 slits per millimeter. the interference pattern is viewed on a screen 1.000 m behind the grating. the first (m = 1) two bright yellow fringes that are visible are 0.7288 m and 0.7300 m from the central maximum. what are the wavelengths of these two fringes?

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?

The motion of water in a dam serves human beings by generating electricity as it is a controlled motion. give one example for an uncontrolled motion. what effects could it cause