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3 years ago

An object has a mass of 12.8 kg and a velocity of 8.4 m/s. what is the kinetic energy of the object?

1 answer:

4 0

Kinetic energy = 1/2 * mass * velocity^2
KE = 1/2*m*v^2

Given m = 12.8 kg, v = 8.4 m/s;

KE = 1/2(12.8)(8.4)^2
KE = 451.58 J
KE = 452 J

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Pete is driving down 7th Street. He drives 300 meters in 18 seconds. Assuming he does not speed up or slow down, what is his spe

Korolek [52]

Answer:

16.67m/s

Explanation:

Given parameters:

Distance Pete drove = 300m

Time taken = 18s

Unknown:

Speed = ?

Solution:

Speed is the distance traveled per unit of time.

It is mathematically expressed as;

Speed = $\frac{distance}{time}$

Insert the parameters and solve;

Speed = $\frac{300}{18}$ = 16.67m/s

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3 years ago

A 0.49 m copper rod with a mass of 0.15 kg carries a current of 13 A in the positive y direction. Let upward be the positive dir

Helen [10]

Answer:

Magnetic field, B = 0.23 T

Explanation:

Given that,

Length of the copper rod, L = 0.49 m

Mass of the copper rod, m = 0.15 kg

Current in rod, I = 13 A (in +ve y direction)

When the rod is placed in magnetic field, the magnetic force is balanced by its weight such that :

$BIL=mg\\\\B=\dfrac{mg}{IL}\\\\B=\dfrac{0.15\times 9.8}{13\times 0.49}\\\\B=0.23\ T$

So, the magnitude of the minimum magnetic field needed to levitate the rod is 0.23 T.

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3 years ago

While filming an intense action sequence for the next James Bond movie, a controlled explosion detonates 1.1 km away from the ac

kolezko [41]

Answer:

The time that will pass between the feeling and hearing the explosion is 2,86 secs

Explanation:

First, let's calculate the time that the wave takes to travel until the actors feel the explosion:

$1,1 km*\frac{1.000 mts}{1 km} *\frac{sec}{3.000 mts} = 0,37 secs$

Now, the time that pass while the actors hear the sound is:

(Remember that the sound speed in the air is 340 m/s on average)

$1,1 km * \frac{1.000 mts}{1 km} * \frac{sec}{340 mts} = 3,23 secs$

So, the time between the feeling and hearing is 3,23 - 0,37 = 2,86 secs

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3 years ago

All sound waves need a(n) _______________________________________ to travel through. 4. _____________________ and ______________

Paha777 [63]

Answer:

Material medium

compressions and rarefactions

Explanation:

A sound wave is an example of a mechanical wave. All mechanical waves require a material medium for propagation. The medium for the propagation of sound is air. This is the reason why, if you cover your mouth, it will be difficult for another person to hear whatever you are saying.

Sound is also a longitudinal wave. Longitudinal waves are described in terms of compressions and rarefactions. Compressions refer to areas where air molecules crowd together while rarefactions refer to areas where the air molecules spread out.

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3 years ago

A collection of 1.25×1019 electrons has the charge -3c, -1c, -2c

djverab [1.8K]

Answer:

-2 C

Explanation:

charge of an electron = - $1.6x10^{-19}C$

therefore charge of 1.25 x $10^{19}$ electrons = $(1.6x10^{-19}) x (-1.25x10^{19})$ = -2 C

3 0

3 years ago