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3 years ago

Just pretend that the cases are numbered 1-5

Physics

1 answer:

Sliva [168]3 years ago

7 0

Answer:

Yes,

NO,

Yes,

No.

Explanation:

CASE: A wire is moved through the field of a magnet

As the wire is moved through the field of a magnetic the magnetic flux through the circuit loop changes,; therefore current is induced.

CASE: A magnet is held close to a wire

There needs to be relative motion between the wire and the magnet for the current to be induced; therefore, simply holding a magnet close to a wire will not induce current in the circuit.

CASE: A magnet is moved into a coil of wire

As the magnet is moved into a coil of wire, the magnetic flux through the coil changes, and therefore, the current is induced.

CASE: A magnet is moved out of coil of wire

Moving a magnet out of coil of wire also changes the magnetic flux through the coil; therefore, the current is induced.

CASE: A magnet rests in coil of wire

There needs to be relative motion between the coil of wire and the magnet for the current to be induced; therefore, a magnet resting in the coil of wire will no induce any current in the coil.

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Energy is conventionally measured in Calories as well as in joules. One Calorie in nutrition is one kilocalorie, defined as 1 kc

Sergeeva-Olga [200]

Answer:

a) The student must run flight of stairs to lose 1.00 kg of fat 709.5 times.

b) Average power

P(w)= 1062.07 [w]

P(hp)=1.42 [hp]

c) This activity is highly unpractical, because the high amount of repetitions he has to due in order to lose, just 1 Kg of fat.

Explanation:

First, lets consider the required amount of work to move the mass of the student. (considering running stairs just as a vertical movement)

Work:

$W= F*d= m*g*d$

Where m is the mass of the student, g is gravity (9.8 m/s) and d is the total distance going up the stairs (0.15m *85steps= 12.75m )

$W= F*d= m*g*d=85* 9.8*12.75=10620.75 [J]$

Converting from Joules to Kcals:

$\frac{10620.75}{4186} =2.537 Kcal$

Now lets take into account the efficiency of the human body (20%)

2.537 ---> 20%

x ---> 100%

$x=\frac{2.537*100}{20} =12.685$

So the student is consuming 12.685 KCals each time he runs up the stairs.

Now,

1 g --> 9 Kcals

1000 g --> 9000KCals

Burning 1 g of fat, requieres 9 KCals, 1000g burns 9000KCals. So in order to burn a 1Kg of fat:

$\frac{9000Kcals}{12.685Kcals} =709.5 times$

He must run up the stairs 709.5 times, to burn 1 Kg of fat.

********************

For b) just converting units, taking into account the time lapse. (53103.75 is the 100% of the energy in joules, from converting 12.685Kcals to joules)

$Power=\frac{Joules}{Seconds} =\frac{53103.75}{50} =1062.075 [W]\\$

$P(hp)=\frac{P(w)}{745.7} =\frac{1062.075}{745.7} =1.42[hp]$

*****

4 0

3 years ago

the magnitude of the magnetic field at point p for a certain electromagnetic wave is 2.21. What is the magnitude of the elctic f

vesna_86 [32]

Answer:

$6.63\times 10^8\ N/C$

Explanation:

Given that,

The magnitude of magnetic field, B = 2.21

We need to find the magnitude of the electric field. Let it is E. So,

$\dfrac{E}{B}=c\\\\E=Bc$

Put all the values,

$E=2.21\times 3\times 10^8\\\\=6.63\times 10^8\ N/C$

So, the magnitude of the electric field is equal to $6.63\times 10^8\ N/C$ .

7 0

2 years ago

Which of the following statements about motion are true? Select all that apply.

Blababa [14]

Answer:

A, C, D

Explanation:

Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force.

and according to Newton's 4th law: An object that is at rest will stay at rest unless a force acts upon it. An object that is in motion will not change its velocity unless a force acts upon it.

4 0

3 years ago

Why are “input” and “output” good words to use when discussing systems?

charle [14.2K]

Answer:

To determine how efficient that system is.

3 0

3 years ago

Read 2 more answers

50 pounds is equal to 22,700 grams. How many pounds does this backpack full of gold weigh? Would you be able to carry out that b

Mariulka [41]

The question is incomplete. Here is the complete question.

7) A standard backpack is approximately 30cm x 30cm x 40cm. Suppose you find a hoard of pure gold (density = 19.3 g/cm³) while treasure hunting in the wilderness. How much mass would your backpack hold if you filled it with gold?

8) 50 pounds is equal to 22,700 grams. How many pounds does this backpack full of gold weigh? Would you be able to carry out that backpack filled with gold?

Answer: 7) m = 694,800g

8) It wieghts 1530.4 lbf

Explanation:

7) Volume of the backpack will be

V = 30 x 30 x 40

V = 36000 cm³

According to density of gold, each cm³ corresponds to 19.3g, then:

m = 19.3 $\frac{g}{cm^{3}}$ * 36000cm³

m = 694800g

If I filled it with gold, the backpack will hold 694800g or 694.8kg.

8) 50 pounds is equal to 22700g. Then:

50 pound = 22700g

W = 694800g

W = $\frac{694800.50}{22700}$

W = 1530.4 lbf

The backpack, in pounds, will weigh 1530.4lbf, which is very heavy to be supported by a human body.

4 0

3 years ago