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cestrela7 [59]
3 years ago
10

A single mass m1 = 4.1 kg hangs from a spring in a motionless elevator. The spring is extended x = 13 cm from its unstretched le

ngth.
Now, three masses m1 = 4.1 kg, m2 = 12.3 kg and m3 = 8.2 kg hang from three identical springs in a motionless elevator. The springs all have the same spring constant that you just calculated above.

Now the elevator is moving downward with a velocity of v = -2.8 m/s but accelerating upward with an acceleration of a = 4.2 m/s2. (Note: an upward acceleration when the elevator is moving down means the elevator is slowing down.)

What is the distance the MIDDLE spring is extended from its unstretched length?
Physics
1 answer:
wlad13 [49]3 years ago
7 0
We know that by Hooke's Law,
F = kx; where F is the net force on the spring, k is the spring constant and x is the extension.
We are told that all the springs have the same spring constant as the first, so we first calculate its spring constant.
F = ma = 4.1 × 9.81
= 40.2 Newtons
k = 40.2 ÷ 0.13
k = 309 Newtons / m
Now, for the spring under consideration, the mass is
m2 = 12.3 kg
The net force will be the difference of the downward force of the mass's weight and the upward force of the elevator. Thus,
F = 12.3 × 9.81 - 12.3 × 4.2
F = 69 Newtons
x = 69 ÷ 309
x = 0.22 m = 22 cm
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In a science demonstration, a teacher mixed zinc (Zn) with hydrogen chloride (HCl) in a flask and quickly attached a balloon ove
Juliette [100K]

Answer:

Combustion reaction resulted in formation of Hydrogen gas.

Explanation:

When zinc and Hydrogen Chloride (HCl) are mixed together, it is a oxidation reduction process. To be specific, a combustion reaction takes place. It is an exothermic reaction. Exothermic reactions involve oxygen and generate . Here, due to this exothermic reaction, Hydrogen gas is being produced which results in the formation of bubble and inflation of balloon.

6 0
3 years ago
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A 1,500 kg car’s speed changes from 30 m/s to 15 m/s after the brakes are applied. Calculate the work done onto the car from the
HACTEHA [7]

The work done onto the car is 506,250 J

The work done on a system implies an increase in the internal energy of the system as a result of some forces acting on the system from the outside.

From the parameters given:

  • The mass of the car = 1500 kg
  • The initial speed = 30 m/s
  • The final speed = 15 m/s

The work done onto the car refers to the change in the kinetic energy (i.e. ΔK.E)

\mathbf{=\dfrac{1}{2} mv_1^2 -\dfrac{1}{2} mv_2^2}

\mathbf{=\dfrac{1}{2} m(v_1^2 - v_2^2)}

\mathbf{=\dfrac{1}{2} \times 1500 \times (30^2 - 15^2)}

= 506,250 J

Therefore, we can conclude that the work done on the car is 506,250 J

Learn more about work done here:

brainly.com/question/18762601

7 0
3 years ago
The inner cylinder of a long, cylindrical capacitor has radius r and linear charge density +λ. It is surrounded by a coaxial cyl
Ulleksa [173]

Hi there!

a)

We can begin by using the equation for energy density.

U = \frac{1}{2}\epsilon_0 E^2

U = Energy (J)

ε₀ = permittivity of free space

E = electric field (V/m)

First, derive the equation for the electric field using Gauss's Law:
\Phi _E = \oint E \cdot dA = \frac{Q_{encl}}{\epsilon_0}

Creating a Gaussian surface being the lateral surface area of a cylinder:
A = 2\pi rL\\\\E \cdot 2\pi rL = \frac{Q_{encl}}{\epsilon_0}\\\\Q = \lambda L\\\\E \cdot 2\pi rL = \frac{\lambda L}{\epsilon_0}\\\\E = \frac{\lambda }{2\pi r \epsilon_0}

Now, we can calculate the energy density using the equation:
U = \frac{1}{2} \epsilon_0 E^2

Plug in the expression for the electric field and solve.

U = \frac{1}{2}\epsilon_0 (\frac{\lambda}{2\pi r \epsilon_0})^2\\\\U = \frac{\lambda^2}{8\pi^2r^2\epsilon_0}

b)

Now, we can integrate over the volume with respect to the radius.

Recall:
V = \pi r^2L \\\\dV = 2\pi rLdr

Now, we can take the integral of the above expression. Let:
r_i = inner cylinder radius

r_o = outer cylindrical shell inner radius

Total energy-field energy:

U = \int\limits^{r_o}_{r_i} {U_D} \, dV =   \int\limits^{r_o}_{r_i} {2\pi rL *U_D} \, dr

Plug in the equation for the electric field energy density and solve.

U =   \int\limits^{r_o}_{r_i} {2\pi rL *\frac{\lambda^2}{8\pi^2r^2\epsilon_0}} \, dr\\\\U = \int\limits^{r_o}_{r_i} { L *\frac{\lambda^2}{4\pi r\epsilon_0}} \, dr\\

Bring constants in front and integrate. Recall the following integration rule:
\int {\frac{1}{x}} \, dx  = ln(x) + C

Now, we can solve!

U = \frac{\lambda^2 L}{4\pi \epsilon_0}\int\limits^{r_o}_{r_i} { \frac{1}{r}} \, dr\\\\\\U = \frac{\lambda^2 L}{4\pi \epsilon_0} ln(r)\left \| {{r_o} \atop {r_i}} \right. \\\\U = \frac{\lambda^2 L}{4\pi \epsilon_0} (ln(r_o) - ln(r_i))\\\\U = \frac{\lambda^2 L}{4\pi \epsilon_0} ln(\frac{r_o}{r_i})

To find the total electric field energy per unit length, we can simply divide by the length, 'L'.

\frac{U}{L} = \frac{\lambda^2 L}{4\pi \epsilon_0} ln(\frac{r_o}{r_i})\frac{1}{L} \\\\\frac{U}{L} = \boxed{\frac{\lambda^2 }{4\pi \epsilon_0} ln(\frac{r_o}{r_i})}

And here's our equation!

3 0
2 years ago
65 Points! 9 Questions!
alekssr [168]

Answer:

energy : the ability to cause change

work : is force x distance or when an object moves a distance due to a specific force (measured in units of newtons-meters)

potential energy  : is stored energy

kinetic energy : is energy in motion

mechanicle energy : the energy of motion such as a moving vechile

thermal energy : total kinetic energy in moving partsticles, like in boiling water (energy of heat)

chemical : energy stored in chemical bonds, like in plants

electromagnetic : waves with electric and magnetic properties , such as light

nuclear energy : energy stored in the nuclear atoms

all dish was from mah brain u better mark meh brainliest >:}

~batmans wife dun dun dun...aka ~serenitybella

5 0
4 years ago
The idea that life could spring from nonliving matter is called?
Alex17521 [72]
Spontaneous generation
5 0
3 years ago
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