повітряна куля до перебуває поблизу до поверхні Землі. Об'єм кулі=300м³. з кулі скинули баласт і вона піднялася на висоту де густина вдвічі менша. Об'єм кулі при підійманні збільшується в 1, 5 разів. зайти масу баласта та ∆m якщо густина поблизу поверхні 1, 29 кг/м³​

1. every day i get up at 6.40. waking up i wash my face, brush my teeth and get dressed. usually for breakfast i eat cookies with tea. i leave at 7.20 or so. i'm going to stop, which is near my house and food on the bus to school.2. my favorite subject in school is history. the lessons of history can learn a lot about how our ancestors lived. i'm sitting on the lessons with anna.3. when the lessons end i just go home. when i get home, the first thing i'm going to eat and rest. and then i sit down to do homework. we ask a lot of homework.4. i watch tv very often, so i have no favorite.5. every sunday i'm meeting with a friend. we go with her to the movies or just walk around the city.6. when i grow up i want to work on the railroad. 7. i go to bed at 23.00. before you go to bed, i listen to music. then i'm going to wash, brush your teeth and go to bed.