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2 years ago

A bullet having the mass of 110g is fired. If it's velocity is 50m/s, calculate the kinetic energy

2 answers:

7 0

$\text{Kinetic energy,}\\\\E_k = \dfrac 12 mv^2\\\\~~~~~=\dfrac 12 \cdot 110 \times 10^{-3} \cdot 50^2\\\\~~~~~=137.5~ \text{J}$

natulia [17]2 years ago

4 0

Answer: 137.5 Joules

Explanation:

The SI units for kinetic energy is Joules, the SI units for mass is kilograms, and the SI units for velocity is meters per second. We are given the mass in grams, so we must convert it to kilograms. There are 1,000 grams in 1 kilogram:

$110g*\frac{1kg}{1000g} =0.11kg$

Kinetic energy is the energy the system has due to its motion. It is defined to be:

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

Plug everything in:

$KE=\frac{1}{2} (0.11kg)(50m/s)^2$

$KE=137.5J$

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When a carpenter shuts off his circular saw, the 10.0 inch diameter blade slows from 4250 rpm to 0.00 in 4.00 s. (a) What is the

MaRussiya [10]

Answer:

(a) $\alpha=-111.26rad/s$

(b) $s=4450.6in$

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First change the units of the velocity, using these equivalents $1rev=2\pi rad$ and $1 min =60s$

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The angular acceleration $\alpha$ the time rate of change of the angular speed $\omega$ according to:

$\alpha=\frac{\Delta \omega}{\Delta t}$

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$\theta = \omega_i t + \frac{1}{2} \alpha t^2$

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c) The displacement is the difference between the original position and the final. But in every complete rotation of the rim, the point returns to its original position. so is needed to know how many rotations did the point in the 890.16 rad of distant traveled:

$\frac{890.12}{2\pi}=141.6667$

The real difference is in the 0.6667 (or 2/3) of the rotation. To find the distance between these positions imagine a triangle formed with the center of the blade (point C), the initial position (point A) and the final position (point B). The angle $\gamma=\frac{2\pi}{3}=\frac{360^o}{3}=120$ is between the two sides known. Using the theorem of the cosine we can find the missing side of the the triangle(which is also the net displacement):

$c^2=a^2+b^2-2abcos(\gamma)$

$c^2=5^2+5^2-2(5)(5)cos(\frac{2\pi}{3} )\\c^2=25+25+25\\c^2=75\\c=5\sqrt{3}=8.66in$

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A bullet having the mass of 110g is fired. If it's velocity is 50m/s, calculate the kinetic energy​

A bullet having the mass of 110g is fired. If it's velocity is 50m/s, calculate the kinetic energy