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2 years ago

5

A rod of length 0.82 m, rotating with an angular speed, 4.2 rad/s, about axes that pass perpendicularly through one end, has a m

ass of 0.63 kg, which is distributed uniformly along its length. Find the kinetic energies of the rod.

1 answer:

mariarad [96]2 years ago

5 0

Answer:

Explanation:

KE = ½Iω²

ΚΕ = ½(mL²/3)ω²

ΚΕ = ½(0.63(0.82²)/3)4.2²

ΚΕ = 1.24541928

KE = 1.2 J

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A generator contains a coil that spins to produce an electric current. How is energy transformed by using a generator

LiRa [457]

<u>Answer </u>

Mechanical energy ⇒ Electric energy

<u>Explanation </u>

A generator is used to produce electric energy. When he coils are made to rotate/spin, is makes the mechanical part. This coils rotates inside a magnetic fields inducing current in the coils. When current starts flowing in the coils, it forms the electrical part.

So, on the generator the energy changes are from mechanical to electrical energy.

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2 years ago

A car traveling at 40 ft/sec decelerates at a constant 5 feet per second per second. how many feet does the car travel before co

Tema [17]

<span>This problem is solved by the equation of motion: x = x0 + v0*t + 1/2*a*t^2, Here x0 = 0, v0 = 40ft/sec and a = -5 ft/s^2, we need to solve for t: v = v0 + a*t, solve how long does it take to stop: 0 = v0 + a*t --> a*t = -v0 --> t = -v0/a -- > 40/5 = 8 seconds to stop. In this time, the car travels x = 0 + 40*8 + 0.5*-5*8^2 ft ~ 160 ft. Answer: The car travels 160 ft.</span>

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2 years ago

How much energy must be added to a bowl of 125 popcorn kernels in order for them to reach a popping temperature of 175°C? Assume

Lisa [10]

Answer:

c) 3176 J

Explanation:

mass of 125 popcorn = 125 x .0001 = . 0125 kg

increase in temperature = 175 - 21 = 154°C

specific heat of popcorn = 1650

heat required to increase temperature

= mass of popcorn x increase in temperature x specific heat

= .0125 x 154 x 1650

= 3176.25 J

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2 years ago

Two car collide in an intersection. The speed limit in that zone is 30 mph. The car (mass of 1250 kg) was going 17.4 m/s (38.9).

Musya8 [376]

Answer:

u₂ = 3.7 m/s

Explanation:

Here, we use the law of conservation of momentum, as follows:

$m_1u_1+m_2u_2=m_1v_1+m_2v_2\\$

where,

m₁ = mass of the car = 1250 kg

m₂ = mass of the truck = 2020 kg

u₁ = initial speed of the car before collision = 17.4 m/s

u₂ = initial speed of the tuck before collision = ?

v₁ = final speed of the car after collision = 6.7 m/s

v₂ = final speed of the truck after collision = 10.3 m/s

Therefore,

$(1250\ kg)(17.4\ m/s)+(2020\ kg)(u_2)=(1250\ kg)(6.7\ m/s)+(2020\ kg)(10.3\ m/s)\\\\(2020\ kg)(u_2) = 8375\ N.s + 20806\ N.s - 21750\ N.s\\\\u_2=\frac{7431\ N.s}{2020\ kg}$

<u>u₂ = 3.7 m/s</u>

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2 years ago

A negatively charged balloon has 4 μC of charge. How many excess electrons are on this bal- loon? The elemental charge is 1.6 ×

bagirrra123 [75]

Data:

The charge of a body depends on the amount of electrons it gains or loses. Q = n * e, where "Q" is charge, "n" is the number of plus or minus electrons, and "e" is the fundamental charge of an electron $1,6 * 10 ^{-19}C$ <span>. To know if the body has gained or lost, we look at the signal of its charge, remembering that the electron is negative. The charge of the body is 4 μC (positive), so there is a lack of electrons!

Q = 4 </span>μC → $Q = 4*10^{-6}$
$e = 1,6 * 10 ^{-19}C$
$n = ?$ <span>

We have:
</span> $Q = n*e$
$n = \frac{Q}{e}$
$n = \frac{4*10^{-6}}{1,6 * 10 ^{-19}}$
$n = 2,5*10^{-6-(-19)}$
$n = 2,5*10^{-6+19}$
$\boxed{n = 2,5*10^{13}electrons}$

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2 years ago