Cho mạch điện như hình vẽ. Biết Umn=18V cường độ dòng điện qua R2 là I2=2A. Tìm a) R1 nếu R2=6 ôm, R3= 3 ôm

b) R3 nếu R1= 3 ôm R2=1 ôm

c) R2 nếu R1=5 ôm, R3= 3 ôm

On a day when the barometer reads 75.23 cm, a reaction vessel holds 250 ml of ideal gas at 20 celsius. an oil manometer ( ρ= 810 kg/m^3) reads the pressure in the vessel to be 41 cm of oil and below atmospheric pressure. what volume will the gas occupy under s.t.p.?

At what time will the interfering waves have an amplitudeof zero?

During a medieval siege of a castle, the attacking army uses a trebuchet to hurl heavy stones at the castle walls. if the trebuchet launches the stones with a velocity of at an angle of 50.0°, (a) how long does it take the stone to hit the ground? (b) what is the maximum distance that the trebuchet can be from the castle wall to be in range? (c) how high will the stones go? show all your work.