Nhiệt lượng của nước 100 tỏa ra:

Q1=m1.c1.(t1-t)

=0,5.4200.(100-t)

Nhiệt lượng của nước ở 30 độ là:

Q2=m2.c2(t-t2)

=0,1.4200.(t-30)

Ta có phương trình cân bằng nhiệt :

Q1 tỏa= Q2 thu

<=>..............

a,70

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.

She helped us a lot with our project. We couldn't continue without her.

A. Provided her contribution wouldn't come, we couldn't have continued with the project.

B. Unless we had her contribution, we couldn't have continued with the project

C. If she hadn't contributed positively, we couldn't have continued with the project

D. But for her contribution, we could have continued with the project

_____ that Marie was able to retire at the age of 50

A. So was her successful business

B. So successful was her business

C. Her business was successful

D. So successful her business was

a, Nhiệt lượng tỏa ra của nước:

Q1=m1.c1.(t1-t)

=1.4200.(100-40)

=70J

b,Ta có pt cân = nhiệt:

Q1 tỏa=Q2 thu

=> Q2 thu=70J

Nhiệt độ tăng của đồng là:

Q2=m2.c2.t

=>t=Q2/m2.c2

=>t=70/0,3.380

=>t=0,6 độ.

TT:

m1=0,2kg

t1=100

t2=20

t=27

------------------

Q1=?

m2=?

Bài làm:

a,Nhiệt lượng quả cầu tỏa ra:

Q1=m1.c1.(t1-t)

=2.880.(100-27)

=12848J

b, Ta có pt cân bàng nhiệt:

Q1 tỏa= Q2 thu

12848=m2.c2.(t-t2)

12848=m2.29400

m2=0,437kg

Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.

The presenter started his speech with a few_____jokes to build rapport with the audience.

A. whole-hearted

B. light-hearted

C. soft-hearted

D. kind-hearted

Read the following passage and mark the letter A, B, C,  D on your answer sheet to indicate the correct answer to each of the questions. Fill in the appropriate word in question 26

        After a busy day of work and play, the body needs to rest. Sleep is necessary for good health. During this time, the body recovers from the (26) ______ of the previous day. The rest that you get while sleeping enables your body to prepare itself for the next day.

        There are four levels of sleep, each being a little (27) ______ than the one before. As you sleep, your muscles relax little by little. Your heart beats more slowly, and your brain slows down. After you (28) _____ the fourth level, your body shifts back and forth from one level of sleep to the other.

        Although your mind slows down, you will dream from time to time. Scientists who study sleep state that when dreaming (29) ______ , your eyeballs begin to move more quickly. This stage of sleep is called REM, which stands for Rapid Eye Movement.

        If you have trouble falling asleep, some people recommend breathing very slowly and deeply. Other people believe that drinking warm milk will make you (30) ______. There is also an old suggestion that counting sheep will put you to sleep!

A. actions

B. activities

C. acts

D. activeness