My Favourite Holiday (Birthday)
My name is Alexandra, I’m thirteen years old. My favourite holiday is my birthday. On this day I get up early, but by that time my mother already cooks food for a festive table in the kitchen. In the morning my family and friends begin to give presents and congratulate me. My parents and younger brother always want me to remember this day for a long time that’s why they decorate the flat with many-coloured little balls.
On this day a lot of my friends and relations usually come to see me. When we all get together we sit down to table and begin to celebrate my birthday. Everybody has a good time dances and communicates with each other, the music plays loudly.
At the end of the holiday we turn off the lights and my father brings a big cake with candles. I must blow out the candles and make a wish. After that we have tea with a cake and then we dismiss the guests. I would like to celebrate my birthday every month because all our relations and friends can meet together on this day.
I grow up every year but my birthday always remains the most unforgettable holiday of the year.
Тело массой 0.2 кг падает с высоты 1 м с ускорением 8 м/с^2. Найти изменение импульса тела за время полета
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Дано:
m=0.2 кг
h=1 м
a=8 м/с²
Найти: ∆p-?
р1 = mV1
p2 = mV2
∆p = р2-p1
∆p = mV2-mV1
т. к. V1=0, то формула принимает вид
∆p = mV2
S=at²/2
t= корень из (2S/a)
t= корень из (2м/8 м/с²)
t= 0.5 с
a = V2-V0/t
V0=0
=>
a = V2/t
V2= at
V2 = 0.8 м/с² × 0.5 с = 0.4 м/с
∆p = 0.4 м/с × 0.2 кг = 0.08 кг × м/с
Объяснение: