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Alex73 [517]
2 years ago
7

Một nười thả 420g chì ở nhiệt độ 100°C và 260g nước ở nhiệt độ 58°C làm cho nước nóng lên tới 60°C . Cho nhiệt dung riêng của nư

ớc là 4200J/kg.K và bảo qua sự hao phí nhiệt ra môi trường bên ngoài . Hãy tính :
a) Nhiệt độ của chì khi có cân bằng nhiệt

b) Nhiệt lượng nước đã thu vào

c) Nhiệt dung riêng của chì

d) Nếu muốn nước và chì nóng tới nhiệt độ 75°C thì cần thêm vào một lượng chì ở nhiệt độ 150°C là bao nhiêu ?
Physics
1 answer:
vlabodo [156]2 years ago
6 0
Hey what language is this?
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Suppose you're performing experiments in science class in which you start with 70 bacteria and the amount of bacteria triples ev
barxatty [35]
1h----------------> 70x3=210 bacteria
2h-----------------> 210*3=630 bactaeria
let be y the number of bacteria at the t=0h
it is y=70 3^0
for t= 1h
y=70*3^1=210
for t=2h
y=70*3^2=630

so we can write y=70*3^x, where x is the number of hour


5 0
3 years ago
Read 2 more answers
You and a partner sit on the floor and stretch out a coiled spring to a length of 7.2 meters. You shake the coil so you
vekshin1

Answer:

Approximately 5.9\; {\rm m\cdot s^{-1}} (assuming that the partner is holding the other end of the coil stationary.)

Explanation:

In a standing wave, an antinode is a point that moves with maximal amplitude, while a node is a point that does not move at all. There is an antinode between every two adjacent nodes. Likewise, there is a node between every two adjacent antinodes.

The side of the spring that is being shaken moving with maximal amplitude. Hence, that point on this spring would also be an antinode. In contrast, the side of the spring that is held still (does not move at all) would be a node.

There would be a node between:

  • the antinode at the end of the spring that is being shaken, and
  • the antinode between the two ends of this spring.

Overall, the nodes and antinodes on this spring would be:

  • node at the end that is being held still,
  • antinode (as mentioned in the question),
  • node (inferred, not mentioned in the question), and
  • antinode at the end that is being shaken.

The distance between two adjacent nodes is equal to one-half (that is, (1/2)) the wavelength of the wave. The distance between a node and an adjacent antinode is one-quarter (that is, (1/4)) of the wavelength of the wave.

Thus, if the wavelength of the wave in this question is \lambda, the length of this spring would be:

\displaystyle \frac{1}{2}\, \lambda + \frac{1}{4}\, \lambda = \frac{3}{4}\, \lambda.

The question states that the length of this coiled spring is 7.2\; {\rm m}. In other words, (3/4) \, \lambda = 7.2\; {\rm m}. The wavelength of this wave would be (7.2\; {\rm m}) / (3/4) = 9.6\; {\rm m}.

The frequency f of this wave is the number of cycles in unit time:

\begin{aligned} f &= \frac{10}{16.3\; {\rm s}} \approx 0.613\; {\rm s^{-1}}\end{aligned}.

Hence, the speed v of this wave would be:

\begin{aligned} v &= \lambda\, f \\ &=9.6\; {\rm m} \times 0.613\; {\rm s^{-1}} \\ &\approx 5.9\; {\rm m \cdot s^{-1}}\end{aligned}.

3 0
2 years ago
How to tell how much work gravity does on something?
Grace [21]
By dropping a ball and seeing how long it takes to hit the ground or throw a ball up and time it as well
4 0
2 years ago
The owners want the speed at the bottom of the first hill doubled. How much higher must the first hill be built?
Sonja [21]
Neglecting friction and air resistance, the first hill must be built 4 times higher than it is now.
3 0
3 years ago
If the given wave has a frequency of 100 Hz, what frequency will the sixth harmonic have?
alukav5142 [94]

Answer:

600Hz

Explanation:

In electrical systems of alternating current, the harmonics are, as in acoustics, frequencies multiples of the fundamental working frequency of the system and whose amplitude decreases as the multiple increases. For example, if we have systems fed by the 50 Hz network, harmonics of 100, 150, 200, etc. may appear.

In our case having a fundamental wave of 100Hz, I can have harmonics of 200,300,400, ..., 600Hz

4 0
3 years ago
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