có một ngôi nhà mái dốc nhà cao 12m mái cao 1,5m rộng 4m người ta bố trí 2 kim thu sét dài bằng nhau tại hai đầu hồi khoảng cách hai kim thu sét là 22m hãy tính chiều cao cảu hai cột thu sét để bảo vệ an toàn cho ngôi nhà

What would the difference of spectral lines emitted by hydrogen gas in distant galaxies which is normally found at a wavelength of 21 cm on earth, be observed at 21.1 centimeters?

Aman tries to push a box of mass 4 kg with a force of 5 n but the box remains stationary if the coefficient of static friction is 0.45, what is the value of the maximum force of friction?

Imagine you had to physically add electrons, one at a time, to a previously neutral conductor. you add one electron very easily, but the second electron requires more work. in your initial post to the discussion, explain why this is. also, what happens to the work needed to add the third, fourth, fifth, and subsequent electrons