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3 years ago

7

A bullet has a speed of 500 m/s as it leaves a rifle. If it is fired horizontally from a cliff 12m above a lake, how far does th

e bullet travel before striking the water?

1 answer:

dem82 [27]3 years ago

3 0

Because you don’t have it

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What is the relationship between electric currents and magnetic fields?

Aleksandr [31]

The electric currents induces a magnetic field. They changing magnetic field can be induce an electric current.

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3 years ago

What is the radius of a tightly wound solenoid of circular cross-section that has 180turns if a change in its internal magnetic

Nata [24]

Answer:

Radius of cross section, r = 0.24 m

Explanation:

It is given that,

Number of turns, N = 180

Change in magnetic field, $\dfrac{dB}{dt}=3\ T/s$

Current, I = 6 A

Resistance of the solenoid, R = 17 ohms

We need to find the radius of the solenoid (r). We know that emf is given by :

$E=N\dfrac{d\phi}{dt}$

$E=N\dfrac{d(BA)}{dt}$

Since, E = IR

$IR=NA\dfrac{dB}{dt}$

$A=\dfrac{IR}{N.\dfrac{dB}{dt}}$

$A=\dfrac{6\ A\times 17\ \Omega}{180\times 3\ T/s}$

$A=0.188\ m^2$

or

$A=0.19\ m^2$

Area of circular cross section is, $A=\pi r^2$

$r=\sqrt{\dfrac{A}{\pi}}$

$r=\sqrt{\dfrac{0.19}{\pi}}$

r = 0.24 m

So, the radius of a tightly wound solenoid of circular cross-section is 0.24 meters. Hence, this is the required solution.

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3 years ago

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

schepotkina [342]

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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3 years ago

A box with sides of length 40 cm is made up of six pieces of concrete of thickness 5 mm. The inside of the box is filled with 10

Damm [24]

Answer:

d)2.13 C s⁻¹

Explanation:

Rate of flow of heat through walls

= $\frac{KA(T_2-T_1)}{d}$

K = .33

A = 6 X .4 X .4 =0.96

T₂-T₁ = 30+40 = 70

d = 5 x 10⁻³

Put these data in the relation above

Rate of flow of heat

= $\frac{.33\times.96\times70}{5\times10^{-3}}$

= 4435.2 Js⁻¹

Specific heat of gas = 2.5 R = 20.785 J

Rise in temp = $\frac{4435.2}{100\times20.785}$

= 2.13 degree celsius.

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3 years ago

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