Giải giúp với ạk.
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50 kW = 50,000W
4500kJ = 4 500 000 J
Thời gian chuyển động là
\(P=\dfrac{A}{t}\Rightarrow t=\dfrac{A}{P}=\dfrac{4,500,000}{50,000}=90\left(s\right)\)
Lực kéo đầu tàu là
\(F=\dfrac{P}{v}=\dfrac{50,000}{10}=5000\left(N\right)\)
25 What are you going to do this week?
26 We might go on holiday to the moon in the future
27 There will be a robot in my house
28 The room is very large
25.What are you going to do this week?
26.We might go on holiday to the moon in the future.
27.There will be have robot in my house.
28.The room is large
Chúc bạn học tốt✔✔
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=9752655002593024-98765431x98765433
=9752655002593024-9754610558146623
= -1955555553599
28 I haven't gone to HCM City for 2 years
29 We have lived in My Tho for ten years
30 Lan didn't go to school last week
31 He was at home yesterday
Question8:
29. We live in Phu Tho about ten years.
30. I will see him tomorrow.
31. Lan didn't go to school last week
32. He was at home yesterday.
a)Công suất hao phí:
\(P_{hp}=\dfrac{P^2\cdot R}{U^2}=I^2\cdot R=100^2\cdot0,2\cdot100=200000W\)
b)Muốn giảm \(P_{hp}\) đi 4 lần thì phải tăng \(U^2=4\Leftrightarrow U=2\) lần vì \(P_{hp}\) tỉ lệ nghịch với bình phương U.