Сколько воды вытесняет плавающий деревянный брус длинной 3 м, шириной 30 см и высотой 20 см? (плотность дерева 600 кг на кубический метр)

определим объем бруса 3*0,3*0,2=0,18 м3

масса 0,18*600=108 кг

сила тяжести mg=108*10=1080 н

на брус действует сила архимеда a=rgvпогр

v=a/rg=mg/rg=1080/1000*10=0,108 м3

4) дано:  

ро ртути = 13600 кг/м^3

h = 76 м = 0.76 м

найти: p

решение:

p = ро * gh =  13600 кг/м^3 * 10 h/кг * 0.76 м = 103360 па

5) f = mg = 0.5 кг * 10 н/кг = 5 н

6) дано:

v = 30 л = 0.03 м^3

ро бензина = 700 кг/м^3

найти: m

решение:  

m = ро * v =  700 кг/м^3 *  0.03 м^3 = 21 кг

7) дано:  

m = 850 г = 0.85 кг

v = 140 см^3 =  0,00014 м^3

ро латуни = 8500 кг/м^3

найти: сплошной или полый

решение:

найдём плотность шара

ро = m/v =  0.85 кг/0,00014 м^3 = ~ 6071 кг/м^3 

6071 кг/м^3 < 8500 кг/м^3, значит полый

8)f = mg = 0.5 кг * 10 н/кг = 5 н

ответ:

если надо ввыучить то выбери

объяснение:

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