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3 years ago

7.

2 answers:

7 0

Contact are those types of forces that result when the two interacting objects are perceived to be physically contacting each other.

Answer: Option B

<u>Explanation:</u>

A contact force is any force that requires contact to occur. Kick a ball or push a desk in a room, driving a car up a hill, are the best daily life examples. Here, the question itself says “contacting”. So, undoubtedly, it is contact forces.

The toy moves because a force is continuously applied by someone on the toy, while in the second case, the given force is applied in the form of impulse. Another contact force, we can simply understand is frictional force.

sukhopar [10]3 years ago

6 0

Answer:

The answer is B, contact!

Explanation:

The two objects are contacting (or interacting) each other.

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The sound level at a distance of 2.30 m from a source is 115 dB. At what distance will the sound level have the following values

Aleksandr [31]

Answer:

distance is 13 m for 100 dB

distance is 409 km for 10 dB

Explanation:

Given data

distance r = 2.30 m

source β = 115 dB

to find out

distance at sound level 100 dB and 10 dB

solution

first we calculate here power and intensity and with this power and intensity we will find distance

we know sound level β = 10 log(I/ $I_{0}$ ) ......................a

put here value (I/ $I_{0}$ ) = 10^−12 W/m² and β = 115

115 = 10 log(I/10^−12)

I = 0.316228 W/m²

and we know power = intensity × 4π r² ...............b

power = 0.316228 × 4π (2.30)²

power = 21.021604 W

we know at 100 dB intensity is 0.01 W/m²

so by equation b

power = intensity × 4π r²

21.021604 = 0.01 × 4π r²

so by solving r

r = 12.933855 m = 13 m

distance is 13 m

and

at 10 dB intensity is 1 × 10^–11 W/m²

so by equation b

power = intensity × 4π r²

21.021604 = 1 × 10^–11 × 4π r²

by solving r we get

r = 409004.412465 m = 409 km

5 0

4 years ago

An emf of 22.0 mV is induced in a 519-turn coil when the current is changing at the rate of 10.0 A/s. What is the magnetic flux

zhenek [66]

Answer:

$\phi=1.56\times 10^{-5}\ Wb$

Explanation:

Given that,

Emf, V = 22 mV

Number of turns in the coil us 519

Rate of change of current is 10 A/s.

We need to find the magnetic flux through each turn of the coil at an instant when the current is 3.70 A.

Let's find the inductance first. So,

$L=\dfrac{\epsilon}{(dI/dt)}\\\\L=\dfrac{0.022}{10}\\\\L=0.0022\ H$

We have,

$L=\dfrac{N\phi}{I}$ , $\phi$ is magnetic flux

$\phi=\dfrac{LI}{N}\\\\\phi=\dfrac{0.0022\times3.7}{519}\\\\\phi=1.56\times 10^{-5}\ Wb$

So, the magnetic flux is $1.56\times 10^{-5}\ Wb$ .

8 0

3 years ago

State the law of conservation of energy

storchak [24]

Answer:

In physics and chemistry, the law of conservation of energy states that the total energy of an isolated system remains constant; it is said to be conserved over time. ... For instance, chemical energy is converted to kinetic energy when a stick of dynamite explodes.

7 0

3 years ago

Which object has the most gravitational potential energy?

Kipish [7]

Answer: An 8 kg book at a height of 3 m has the most gravitational potential energy.

Explanation:

Gravitational potential energy is the product of mass of object, height of object and gravitational field.

So, formula to calculate gravitational potential energy is as follows.

U = mgh

where,

m = mass of object

g = gravitational field = $9.81 m/s^{2}$

h = height of object

(A) m = 5 kg and h = 2m

Therefore, its gravitational potential energy is calculated as follows.

$U = mgh\\= 5 kg \times 9.81 m/s^{2} \times 2 m\\= 98.1 J (1 J = kg m^{2}/s^{2})$

(B) m = 8 kg and h = 2 m

Therefore, its gravitational potential energy is calculated as follows.

$U = mgh\\= 8 kg \times 9.81 m/s^{2} \times 2 m\\= 156.96 J (1 J = kg m^{2}/s^{2})$

(C) m = 8 kg and h = 3 m

Therefore, its gravitational potential energy is calculated as follows.

$U = mgh\\= 8 kg \times 9.81 m/s^{2} \times 3 m\\= 235.44 J (1 J = kg m^{2}/s^{2})$

(D) m = 5 kg and h = 3 m

Therefore, its gravitational potential energy is calculated as follows.

$U = mgh\\= 5 kg \times 9.81 m/s^{2} \times 3 m\\= 147.15 J (1 J = kg m^{2}/s^{2})$

Thus, we can conclude that an 8 kg book at a height of 3 m has the most gravitational potential energy.

3 0

3 years ago

¿Cuál es la aceleración centrípeta de un móvil que recorre una

Lady bird [3.3K]

Answer:

a) a = 4.57 m/s², b) a = 6.48 m / s² , c) a = 1.42 m / s²,d) r = 82.3 m

Explanation:

The centripetal acceleration is the acceleration responsible for the change of direction of the acceleration vector and occurs in circular movements, the expression is

a = v² / r

let's apply this precaution to our cases

a) let's calculate

a = 8²/14

a = 4.57 m/s²

b) an automobile at v = 65 km / h (1000 m / 1km) (1 h / 3600 s) =18,055 m/s

let's reduce feet to meters

1 ft = 0.3048 m

r = 165 ft (0.3048 m / 1 ft) = 50.292 m

a = 18,055 2 / 50,292

a = 6.48 m / s²

c) we calculate

a = 1.25²2 / 1.1

a = 1.42 m / s²

d) we look for the radius

a = v² / r

r = v² / a

we reduce

v = 80 km / h (1000 m / 1km) (1h / 3600s) = 22.22 ms

r = 22.22²/6

r = 82.3 m

e) the cenripeta acceleration is used to take the curves on the highway,

Used in centrifuges to separate compounds

It is used in the games of the park of atraccio

Used in CD players and computer hard drives

5 0

3 years ago