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3 years ago

Do all engines operate at less than 100 percent efficiency because they conduct heat

Physics

2 answers:

Alika [10]3 years ago

4 0

all engines operate at less than 100 percent efficiency because they EMIT heat. ;)

Julli [10]3 years ago

3 0

They EMIT heat is the correct answer

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In order for the ball to be able to make a complete circle around the peg, there must be sufficient speed at the top of its arc

Vesna [10]

Answer:

Explanation:

Let T be the tension in the swing

At top point $mg-T=\frac{mv^2}{r}$

where v=velocity needed to complete circular path

r=distance between point of rotation to the ball center=L+\frac{d}{2} (d=diameter of ball)

Th-resold velocity is given by $mg-0=\frac{mv^2}{r}$

To get the velocity at bottom conserve energy at Top and bottom

At top $E_T=mg\times 2L+\frac{mv^2}{2}$

Energy at Bottom $E_b=\frac{mv_0^2}{2}$

Comparing two as energy is conserved

$v_0^2=4gr+gr$

$v_0^2=5gr$

$v_0=\sqrt{5gr}$

$v_0=\sqrt{5g\left ( \frac{d}{2}+L\right )}$

6 0

3 years ago

Frank has a sample of steel that has a mass of 80 grams if the density is 8g/cm3 what is the volume

nikklg [1K]

Density is mass divided by volume. rho=m/v. So, v=m/rho. In frank's case this is 80/8 = 10 cm^3.

7 0

4 years ago

Help fill in the blanks please

vampirchik [111]

..because the energy put in to making bonds is greater than the energy given back from breaking bonds.
The exothermic part of the reaction is greater than the endothermic part.

8 0

3 years ago

A diode has a power rating of 5W. If the diode voltage is 3.6V and the diode current is 1.75A, what is the power dissipation?

son4ous [18]

Answer:

Explanation:

Power = current * voltage

Power = 3.6 * 1.75

Power = 6.3 watts.

I hope this diode does not have to do this for very long. The power dissipation is above the diode's rated power -- a condition that won't last forever.

The power dissipation is 6.3 watts.

4 0

3 years ago

The energy levels of one‑electron ions are given by the equation En=(−2.18×10−18 J)(Z^2/n^2) where Z is atomic number and n is t

Alexxandr [17]

Answer:

$\lambda=4.86*10^{-7}m$

Explanation:

Using the given equation, we calculate the energy associated with the excited state $n_i=8$ and $n_f=4$

$E_n=\frac{-2.18*10^-18J(Z^2)}{n^2}$

Helium has an atomic number (Z) equal to 2, for n=8:

$E_8=\frac{-2.18*10^{-18}J(2^2)}{8^2}\\E_8=-1.36*10{-19}J$

For n=4:

$E_4=\frac{-2.18*10^{-18}J(2^2)}{4^2}\\E_4=-5.45*10{-19}J$

When an electron jumps from an energy level with greater energy $E_i$ to one with lower energy $E_f$ the wavelength of the emitted photon is given by:

$\lambda=\frac{hc}{E_i-E_f}$

h is the Planck constant and c the speed of light in vaccum. So, we have:

$\lambda=\frac{hc}{E_8-E_4}\\\lambda=\frac{6.63*10^{-34}J \cdot s(3*10^8\frac{m}{s})}{-1.36*10{-19}J-(-5.45*10{-19}J)}\\\lambda=4.86*10^{-7}m$

5 0

3 years ago