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3 years ago

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A barbellbell is loaded with two 20 kg plates on its right side and two 20kg plates on its left side. The barbell is 2.2m long,

and its unloaded mass is 20kg. The two 20kg plates on the right side are locked in place at 35cm and 40cm from the right end of the bar. The two 20kg plates on the left side have slipped one iss 30 cm from the left end of the bar and the other is 20 cm from the left end of th bar. where is the center of gravity of this bar?

1 answer:

Aleks [24]3 years ago

7 0

Answer:

<h2>Center of gravity of the system of all masses is 105 cm from the left end of the rod</h2>

Explanation:

Let the position of Left end of the rod is our reference

So here we will have

$m_1 = 20 kg$

$x_1 = 20 cm$

$m_2 = 20 kg$

$x_2 = 30 cm$

$m_3 = 20 kg$

$x_3 = 110 cm$

$m_4 = 20 kg$

$x_4 = (220 - 40) = 180 cm$

$m_5 = 20 kg$

$x_5 = (220 - 35) = 185 cm$

so we will have

$x_{cm} = \frac{m_1x_1 + m_2x_2 + m_3x_3 + m_4x_4 + m_5x_5}{m_1 + m_2 + m_3 + m_4 + m_5}$

$x_{cm} = \frac{20(20 + 30 + 110 + 180 + 185)}{20 + 20 + 20 + 20 + 20}$

$x_{cm} = 105 cm$

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A 0.150 kg stone rests on a frictionless, horizontal surface. A bullet of mass 9.50 g, traveling horizontally at 380 m/s, strike

Anvisha [2.4K]

Answer:

(a)Magnitude=28.81 m/s

Direction=33.3 degree below the horizontal

(b) No, it is not perfectly elastic collision

Explanation:

We are given that

Mass of stone, M=0.150 kg

Mass of bullet, m=9.50 g= $9.50\times 10^{3} kg$

Initial speed of bullet, u=380 m/s

Initial speed of stone, U=0

Final speed of bullet, v=250m/s

a. We have to find the magnitude and direction of the velocity of the stone after it is struck.

Using conservation of momentum

$mu+ MU=mv+ MV$

Substitute the values

$9.5\times 10^{-3}\times 380 i+0.150(0)=9.5\times 10^{-3} (250)j+0.150V$

$3.61i=2.375j+0.150V$

$3.61 i-2.375j=0.150V$

$V=\frac{1}{0.150}(3.61 i-2.375j)$

$V=24.07i-15.83j$

Magnitude of velocity of stone

= $\sqrt{(24.07)^2+(-15.83)^2}$

|V|=28.81 m/s

Hence, the magnitude and direction of the velocity of the stone after it is struck, |V|=28.81 m/s

Direction

$\theta=tan^{-1}(\frac{y}{x})$

= $tan^{-1}(\frac{-15.83}{24.07})$

$\theta=tan^{-1}(-0.657)$

=33.3 degree below the horizontal

(b)

Initial kinetic energy

$K_i=\frac{1}{2}mu^2+0=\frac{1}{2}(9.5\times 10^{-3})(380)^2$

$K_i=685.9 J$

Final kinetic energy

$K_f=\frac{1}{2}mv^2+\frac{1}{2}MV^2$

= $\frac{1}{2}(9.5\times 10^{-3})(250)^2+\frac{1}{2}(0.150)(28.81)^2$

$K_f=359.12 J$

Initial kinetic energy is not equal to final kinetic energy. Hence, the collision is not perfectly elastic collision.

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As you may well know, placing metal objects inside a microwave oven can generate sparks. Two of your friends are arguing over th

Fofino [41]

Answer:

$5.04\cdot 10^8 A$

Explanation:

The work function of the metal corresponds to the minimum energy needed to extract a photoelectron from the metal. In this case, it is:

$\phi = 3.950\cdot 10^{-19}J$

So, the energy of the incoming photon hitting on the metal must be at least equal to this value.

The energy of a photon is given by

$E=\frac{hc}{\lambda}$

where

h is the Planck's constant

c is the speed of light

$\lambda$ is the wavelength of the photon

Using $E=\phi$ and solving for $\lambda$ , we find the maximum wavelength of the radiation that will eject electrons from the metal:

$\lambda=\frac{hc}{E}=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{3.950\cdot 10^{-19} J}=5.04\cdot 10^{-7}m$

And since

1 angstrom = $10^{-15}m$

The wavelength in angstroms is

$\lambda=\frac{5.04\cdot 10^{-7} m}{10^{-15} m/A}=5.04\cdot 10^8 A$

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3 years ago

Marco is conducting an experiment. He knows the wave that he is working with has a wavelength of 32. 4 cm. If he measures the fr

sineoko [7]

The true statement about the wave is that, the wave has traveled 97. 2 cm in 1 second.

In Physics, we define a wave as a disturbance along a medium that transfers energy. The wavelength of a wave is the distance covered by the wave while the frequency of the wave is the number of cycles of the wave completed per second.

The period of the wave is the inverse of the frequency of the wave. It is defined as the time taken for the wave to complete a cycle and it is measured in seconds.

The wave formula is given as;

v = λf

v = velocity of the wave (distance traveled by the wave in one second)

λ = wavelength of the wave

f = frequency of the wave

So;

λ = 32.4 cm

f = 3 hertz

v = 32.4 cm × 3 hertz

v = 97. 2 cms-1

Hence, the true statement about the wave is that, the wave has traveled 97. 2 cm in 1 second.

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2 years ago

Can the boiling point of water exceed 100c

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Superheated water is liquid water under pressure at temperatures between the usual boiling point, 100c (212 F ) and the critical temperature , 374 C (705F) . It is also known as “subcritical water”
Or “pressurized hot water”.

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3 years ago

How are magnetic poles and electrical charges similar? A. Their same forces repel each other, and their opposite forces attract

melomori [17]

Answer:

A. Their same forces repel each other, and their opposite forces attract each other.

Explanation:

As we know by the property of electric charge that similar charges repel each other and opposite charges attracts each other

So here we have similar situation in magnets also

Two similar poles or like poles of magnet i.e. North - North poles or South - South poles always repel each other

And also we can see that opposite poles of magnet each other i.e. North pole and south pole always attract each other.

SO here correct answer is

A. Their same forces repel each other, and their opposite forces attract each other.

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3 years ago