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3 years ago

8

What is the current in a series circuit with a resistance of 30 ohms and a potential difference of 120 volts?

1 answer:

mars1129 [50]3 years ago

7 0

0.25A....................

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In a crash or collision, why is it advantageous for an occupant to extend the time during which the collision is taking place?

Veseljchak [2.6K]

Answer:

Explanation:

During a car collision momentum of vehicle ceases within a fraction of seconds so Force due to the impulse is huge.

Impulse is defined as the product of average force and time. If we can increase the period of collision for the same impulse then the average force imparted will be less.

If we can increase the time period then damage due to collision will be less.

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3 years ago

A block of unknown mass is attached to a spring with a spring constant of 7.00 N/m 2 and undergoes simple harmonic motion with a

KatRina [158]

Answers:

a) $0.80 kg$

b) $2.12 s$

c) $1.093 m/s^{2}$

Explanation:

We have the following data:

$k=7 N/m$ is the spring constant

$A=12.5 cm \frac{1 m}{100 cm}=0.125 m$ is the amplitude of oscillation

$V=32 cm/s=0.32 m/s$ is the velocity of the block when $x=\frac{A}{2}=0.0625 m$

Now let's begin with the answers:

<h3>a) Mass of the block</h3>

We can solve this by the conservation of energy principle:

$U_{o}+K_{o}=U_{f}+K_{f}$ (1)

Where:

$U_{o}=k\frac{A^{2}}{2}$ is the initial potential energy

$K_{o}=0$ is the initial kinetic energy

$U_{f}=k\frac{x^{2}}{2}$ is the final potential energy

$K_{f}=\frac{1}{2} m V^{2}$ is the final kinetic energy

Then:

$k\frac{A^{2}}{2}=k\frac{x^{2}}{2}+\frac{1}{2} m V^{2}$ (2)

Isolating $m$ :

$m=\frac{k(A^{2}-x^{2})}{V^{2}}$ (3)

$m=\frac{7 N/m((0.125 m)^{2}-(0.0625 m)^{2})}{(0.32 m/s)^{2}}$ (4)

$m=0.80 kg$ (5)

<h3>b) Period</h3>

The period $T$ is given by:

$T=2 \pi \sqrt{\frac{m}{k}}$ (6)

Substituting (5) in (6):

$T=2 \pi \sqrt{\frac{0.80 kg}{7 N/m}}$ (7)

$T=2.12 s$ (8)

<h3>c) Maximum acceleration</h3>

The maximum acceleration $a_{max}$ is when the force is maximum $F_{max}$ , as well :

$F_{max}=m.a_{max}=k.x_{max}$ (9)

Being $x_{max}=A$

Hence:

$m.a_{max}=kA$ (10)

Finding $a_{max}$ :

$a_{max}=\frac{kA}{m}$ (11)

$a_{max}=\frac{(7 N/m)(0.125 m)}{0.80 kg}$ (12)

Finally:

$a_{max}=1.093 m/s^{2}$

5 0

3 years ago

During lightning strikes from a cloud to the ground, currents as high as 2.50×104 A can occur and last for about 40.0 μs . How m

Nezavi [6.7K]

Answer:

<h3>The charge transferred from the cloud to earth is 1 Coulomb.</h3>

Explanation:

Given :

Current $I = 2.5 \times 10^{4}$ A

Time $t = 40 \times 10^{-6}$ sec

We know that the current is the rate of flow of charge.

From the formula of current,

<h3> $I = \frac{Q}{t}$ </h3>

Where $Q =$ charge transfer between cloud and earth.

$Q =I t$

$Q = 2.5 \times 10^{4} \times 40 \times 10^{-6}$

$Q = 1$ C

Hence, the charge transferred from the cloud to earth is 1 Coulomb.

3 0

4 years ago

Where are the oldest rocks found ?

nignag [31]

Answer:

zircons

Explanation:

they are over 4.375 billion years old

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3 years ago

Which rf characteristic best determines the range of a 2.4 ghz ism signal?

Rainbow [258]

<span>The radio frequency characteristic that best determines the range of a 2.4 GHz ism signal is the wavelength.

This frequency can be used in WiFi and can reach up to 46 meters when indoors and about 92 meters when outdoors.
</span><span>
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3 0

3 years ago