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3 years ago

NEED ANSWERED ASAP!! will give brainliest!

1 answer:

8 0

The kinetic energy of any moving object is

K.E. = (1/2) (mass) (speed)² .

To use this simple formula, the 'mass' has to be in kilograms,
and the 'speed' has to be in meters-per-second.

You can see that we have a slight problem that has to be cleaned up:
The speed in the question is given in "kilometers per hour", but we'll
need it in "meters per second". So let's convert that right now:

(600 km/hour) x (1 hour / 3600 seconds) x (1000 meters / km)

= (600 x 1 x 1000 / 3600) (km-hour-meters / hour-second-km)

= 166.67 meters/second .

Now we're ready to plug numbers into the formula for K.E.

(1/2) (mass) (speed)²

= (1/2) (80,000 kg) (166.67 m/s)²

= (40,000 kg) (27,777.8 m²/s²)

= 1,111,111,111 kg-m²/s²

= 1.1... x 10⁹ Joules (choice D)

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Both positive work and negative work have meaning: Positive work follows when the force has a component parallel to the displacement. Positive work adds energy to a system. Negative work follows when the force has a component opposite or against the displacement.

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2 years ago

at room temperature, iron is a solid and mercury is a liquid. based on this information we can infer thata. iron has a higher bo

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8 0

3 years ago

Read 2 more answers

A battery charger can produce 3A at 12 Volt and charges a battery fer 2 hr. Calculate work in KJ.

Oksi-84 [34.3K]

Answer: 259.2 KJ

Explanation:

The formula calculate work don in a circuit is given by :-

$W=QV$ , where Q is charge and V is the potential difference.

The formula to calculate charge in circuit :-

$Q=It$ , where I is current and t is time.

Given : Current : $I=3A$

Potential difference : $V=12\ V$

Time : $t=2\ hr=2(3600)\text{ seconds}=7200\text{ seconds}$

Now, $Q=3(7200)=21,600\ C$

Then, $W=(21600)(12)=259,200\text{ Joules}=259.2\text{ KJ}$

Hence, the work done = 259.2 KJ

4 0

3 years ago

A wave is 8 meters long and has a frequency of 3 Hz. Find speed

Olenka [21]

Answer:

The speed is 24 $\frac{meter}{s}$

Explanation:

A wave is a disturbance that propagates through a certain medium or in a vacuum, with transport of energy but without transport of matter.

The wavelength is the minimum distance between two successive points of the wave that are in the same state of vibration. It is expressed in units of length (m).

Frequency is the number of vibrations that occur in a unit of time. Its unit is s⁻¹ or hertz (Hz).

The speed of propagation is the speed with which the wave propagates in the middle, that is, the magnitude that measures the speed at which the wave disturbance propagates along its displacement. Relate wavelength (λ) and frequency (f) inversely proportionally using the following equation:

v = f * λ.

In this case, λ= 8 meter and f= 3 Hz

Then:

v= 3 Hz* 8 meter

So:

v= 24 $\frac{meter}{s}$

The speed is 24 $\frac{meter}{s}$

5 0

3 years ago

How would a spinning disk's kinetic energy change if its moment of inertia was five times larger but its angular speed was five

Keith_Richards [23]

Answer:

The kinetic energy of a spinning disk will be reduced to a tenth of its initial kinetic energy if its moment of inertia is made five times larger, but its angular speed is made five times smaller.

Explanation:

Let us first consider the initial characteristics of the angular motion of the disk

moment of inertia = $I$

angular speed = ω

For the second case, we consider the characteristics to now be

moment of inertia = $5I$ (five times larger)

angular speed = ω/5 (five times smaller)

Recall that the kinetic energy of a spinning body is given as

$KE = \frac{1}{2}Iw^{2}$

therefore,

for the first case, the K.E. is given as

$KE = \frac{1}{2}Iw^{2}$

and for the second case, the K.E. is given as

$KE = \frac{1}{2}(5I)(\frac{w}{5} )^{2} = \frac{5}{50}Iw^{2}$

$KE = \frac{1}{10}Iw^{2}$

this is one-tenth the kinetic energy before its spinning characteristics were changed.

This implies that the kinetic energy of the spinning disk will be reduced to a tenth of its initial kinetic energy if its moment of inertia is made five times larger, but its angular speed is made five times smaller.

6 0

3 years ago