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Ghella [55]
2 years ago
14

Newton's law of cooling states that the temperature of an object changes at a rate proportional to the difference between its te

mperature and that of its surroundings. Suppose that the temperature of a cup of coffee obeys Newton's law of cooling. If the coffee has a temperature of 185 degrees Fahrenheit when freshly poured, and 3 minutes later has cooled to 172 degrees in a room at 78 degrees, determine when the coffee reaches a temperature of 147 degrees.
Physics
1 answer:
schepotkina [342]2 years ago
4 0

Answer:

6.77 minutes

Explanation:

172 degree - 78 degree = (185 degree - 78 degree)e−2 k

=> 94 = 107

e−2 k => 94 ÷ 107

k => ln (94÷107) / 2

147 - 78 = (185 - 78)e ^[ln (94÷107) / 2]

=> 69 = 107 e^ [ln (94÷107) / 2]

e^[ln (94÷107) / 2] =69 ÷ 107

=> t = [ln (69 ÷ 107)] ÷ [ln (94÷107) / 2]

t=> -0.4387 ÷ -0.0648

t => 6.77 minutes.

Therefore, the final answer to the question is 6.77 minutes.

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What is it called when data are arranged in rows and columns?
Tpy6a [65]

Answer:

C. Table

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A organized collection of records is called a database table. The main key that uniquely identifies each row in the table. Since no two rows may have the same instantaneous value thanks to a unique key, it is simple to choose a row by its main key. A table can also contain several columns, each of which can hold a distinct kind of data. The information stored is verified using the column name and data type.  

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Any field in the data table can be referenced by the secondary key. A database's data field may be a string, a number, a date, or a time. A table's first field should always be the main key, followed by any foreign keys. Actual data should never be present in a primary key. Since the immediate key value is derived from external sources, it is crucial to use it properly. Otherwise, data input mistakes may occur.

The information kept in the database table is referred to as a secondary key. This kind is a primary key, which implies it is a secondary key. A primary key can be used as an alternate key to distinguish between different records in a table and to uniquely identify a record inside a database. Multiple fields that can be either main or alternative make up a composite key.

Depending on the type of data being stored and its intended use, a database table may have a single row or several. The main key determines the number of rows, which might be 50 or more. A secondary key can be used to establish connections between various tables and to distinguish between various data types in a database. A data table also includes a secondary key, which is essential for data retrieval and is separate from the primary key.

You can have local or global database tables. The two types of tables differ in terms of names, availability, and visibility. A global table is accessible to all users and may be utilized by any other user, while a local table is only visible to the present user. It is distinct from a typical table and requires more effort to build than a straightforward one does. Its main function is to maintain a database and store data.

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There is no limit to the amount of rows and columns in a database table. Up to 1,024 rows are allowed in a typical user-defined table. The server's storage capacity determines how many rows can fit in a database table. A table can have characteristics added to it in addition to the column and row. A restriction can stop a row from having empty fields. The connection between two tables can be established via an important control.

8 0
2 years ago
Read 2 more answers
Gayle runs at a speed of 3.85 m/s and dives on a sled, initially at rest on the top of a frictionless snow-covered hill. After s
enot [183]

Answer:

Final velocity at the bottom of hill is 15.56 m/s.

Explanation:

The given problem can be divided into four parts:

1. Use conservation of momentum to determine the speed of the combined mass (Gayle and sled)

From the law of conservation of momentum (perfectly inelastic collision), the combined velocity is given as:  

p_i = p_f  

m_1u_1 + m_2v_2 = (m_1 + m_2)v

v = \frac{(m_1u_1 + m_2v_2)}{(m_1 + m_2)}

v=\frac{[50.0\ kg)(3.85\ m/s) + 0]}{(50.0\ kg + 5.00\ kg)}= 3.5\ m/s  

2. Use conservation of energy to determine the speed after traveling a vertical height of 5 m.

The velocity of Gayle and sled at the instant her brother jumps on is found from the law of conservation of energy:  

E(i) = E(f)  

KE(i) + PE(i) = KE(f) + PE(f)  

0.5mv^2(i) + mgh(i) = 0.5mv^2(f) + mgh(f)  

v(f) = \sqrt{[v^2(i) + 2g(h(i) - h(f))]}

Here, initial velocity is the final velocity from the first stage. Therefore:  

v(f) = \sqrt{[(3.5)^2+2(9.8)(5.00-0)]}= 10.5\ m/s

3. Use conservation of momentum to find the combined speed of Gayle and her brother.  

Given:

Initial velocity of Gayle and sled is, u_1(i)=10.5 m/s

Initial velocity of her brother is, u_2(i)=0 m/s

Mass of Gayle and sled is, m_1=55.0 kg

Mass of her brother is, m_2=30.0 kg

Final combined velocity is given as:

v(f) = \frac{[m_1u_1(i) + m_2u_2(i)]}{(m_1 + m_2)}  

v(f)=\frac{[(55.0)(10.5) + 0]}{(55.0+30.0)}= 6.79 m/s  

4. Finally, use conservation of energy to determine the final speed at the bottom of the hill.

Using conservation of energy, the final velocity at the bottom of the hill is:  

E(i) = E(f)  

KE(i) + PE(i) = KE(f) + PE(f)  

0.5mv^2(i) + mgh(i) = 0.5mv^2(f) + mgh(f)  

v(f) = \sqrt{[v^2(i) + 2g(h(i) - h(f))]} \\v(f)=\sqrt{[(6.79)^2 + 2(9.8)(15 - 5.00)]}\\v(f)= 15.56\ m/s

6 0
2 years ago
A balloon will stick to a wooden wall if the balloon is charged
grigory [225]
<h2>Answer: either way</h2>

The balloon contains neutral charge atoms, that is, it has the same number of electrons (negative charge), protons (positive charge) and neutrons (no charge).

Then, when two objects come into contact, the electrons of one of them can become part of the other.

Thus, by bringing the balloon closer to the wall, the wall, which is also made up of atoms, will reorder its charges in such a way that its electrons or protons become part of the balloon, charging it.

7 0
2 years ago
It is 5.5 km from your home to the physics lab. As part of your physical fitness program, you could run that distance at 10 km/h
stealth61 [152]

Explanation:

Displacement = 5 km

A.

Converting km/h to m/s,

10 km/h * 1000 m/1 km * 1 h/3600 s

= 25/9 m/s

Remember,

700 watt = 700 J/s

Velocity = displacement/time

Time = 5000/(25/9)

= 1800 s

Energy = power * time

= 700 * 1800

= 1,260,000

= 1260 kJ

B.

Converting km/h to m/s,

3 km/h * 1000 m/1 km * 1 h/3600 s

= 5/6 m/s

290 watt = 290 J/s

Velocity = displacement/time

Time = 5000/(5/6)

= 6000 s

Energy = power * time

= 290 * 6000

= 1,740,000

= 1740 kJ

C.

Walking burns more energy; 1,740,000 joules. It burns more because you walk for a greater period of time.

6 0
3 years ago
Please HELP!!
Rudik [331]

Answer:

I think is 2.

Explanation:

(The entire range of wavelengths or frequencies of electromagnetic radiation extending from gamma rays to the longest radio waves and including visible light)

7 0
3 years ago
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