What causes the balloon to move along the string?

A student does 25 J of work on the handle of a pencil sharpener. If the pencil sharpener does 20 J of work on the pencil, what i

allsm [11]

Answer:

80%

Explanation:

Efficiency of machine = work output/work input ×100 %

From question, work output = 20J

Work input = 25J.

Therefore efficiency = 20/25 × 100 %

Efficiency = 20×4 %

Efficiency = 80%

I hope this was helpful, please mark as brainliest

3 0

3 years ago

A recent study found that electrons that have energies between 3.45 eV and 19.9 eV can cause breaks in a DNA molecule even thoug

vlada-n [284]

Answer:

The Minimum wavelength is $\lambda_{min}= 382.2nm$

The Maximum wavelength is $\lambda_{max}= 624.2nm$

Explanation:

From the question we are told that

The energy range is $E_r = 3.25eV \ and \ 19.9eV$

Considering $E = 19.9eV$

When a single photon is transferred to to an electron the energy obtained can be calculated as follows

$E = 19.9eV = 19.9 *1.6 *10^{-19}J$

This energy is mathematically represented as

$E = \frac{hc}{\lambda_{max}}$

Here h is the Planck's constant with value of $h= 6.625*10^{-34}J\cdot s$

c is the speed of light with value of $c = 3*10^8 m/s$

Substituting values and making $\lambda$ the subject of the formula

$\lambda_{max} = \frac{hc}{E}$

$= \frac{6.625*10^{-34} * 3.0*10^{8}}{19.9*1.6*10^{-19}}$

$\lambda_{max}= 624.2nm$

Considering $E = 3.25eV$

When a single photon is transferred to to an electron the energy obtained can be calculated as follows

$E = 19.9eV = 3.25 *1.6 *10^{-19}J$

This energy is mathematically represented as

$E = \frac{hc}{\lambda_{min}}$

Substituting values and making $\lambda$ the subject of the formula

$\lambda_{min} = \frac{hc}{E}$

$= \frac{6.625*10^{-34} * 3.0*10^{8}}{3.25*1.6*10^{-19}}$

$\lambda_{min}= 382.2nm$

3 0

3 years ago

PLEASE HELP MEEEE <br>marking brainliest

aniked [119]

Answer:

Option C

Explanation:

Centripetal acceleration formula regarding velocity and radius is,

$a_c=\frac{v^2}{r}$

now we know the centripetal acceleration is 9 and the radius is 16 so we plug these values into our formula,

$a_c=\frac{v^2}{r}\\\\9=\frac{v^2}{16} \\\\144=v^2\\\\\sqrt{144}=v \\\\v=12\ m/s$

so velocity is 12 m/s

Now for the angular velocity, the formula of centripetal acceleration regarding angular velocity and radius is,

$a_c=rw^2$

we know the centripetal acceleration is 9 and the radius is 16 so plug these values into the formula,

$a_c=rw^2\\\\9=16w^2\\\\0.5625=w^2\\\\\sqrt{0.5625}=w \\\\0.75\ rad/s=w\\$

so angular velocity is 0.75 rad/s

8 0

3 years ago

Scientific inquiry includes many different activities. Which of the following is a process that is typically performed during a

Juli2301 [7.4K]

D. All of these, they’re all part of scientific inquiry

7 0

3 years ago

Read 2 more answers

Relate the structure of water to its ability to act as a solvent

pishuonlain [190]

Explanation:

Water (H2O) as a polar covalent molecule has its arrangement of oxygen and hydrogen atoms where one end (hydrogen) has a partially positive charge while the other side (oxygen) had a partially negative charge.

It is also capable of forming hydrogen bonds with polar molecules. Each water molecule can form two hydrogen bonds involving their hydrogen atoms and two further hydrogen bonds using the hydrogen atoms attached to neighboring water molecules.

5 0

3 years ago