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2 years ago

A student lifts a 90 pound (lb) ball 4 feet (ft) in 5 seconds (s). How many joules of work has the student completed?

1 answer:

7 0

Wending your way through this question and the list of choices
is like running through a corn-maze on a moonless night with
your eyes closed.

Work = (force) x (distance)

Keeping with the units used In the question ...

   Work = (90 pounds) x (4 feet) = 360 foot-pounds .

If you want the work expressed in joules, then you need to convert
pounds and feet to newtons and meters.

   (90 pounds) x (4.448 newtons/pound) = 400.32 Newtons

   (4 feet) x (1 meter / 3.28084 feet) = 1.219 meters

Work = (force) x (distance)

      = (400.32 newtons) x (1.219 meters) = 488.1 joules .

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2 years ago

The first ionization energy of a hydrogen atom is 2.18 aj (attojoules). what is the frequency and wavelength, in nanometers, of

jasenka [17]

1) Frequency: $3.29\cdot 10^{15}Hz$

the energy of the photon absorbed must be equal to the ionization enegy of the atom, which is

$E=2.18 aJ=2.18\cdot 10^{-18} J$

The energy of a photon is given by

$E=hf$

where $h=6.63\cdot 10^{-34}Js$ is the Planck's constant. By using the energy written above and by re-arranging thsi formula, we can calculate the frequency of the photon:

$f=\frac{E}{h}=\frac{2.18\cdot 10^{-18} J}{6.63\cdot 10^{-34} Js}=3.29\cdot 10^{15} Hz$

2) Wavelength: 91.2 nm

The wavelength of the photon can be found from its frequency, by using the following relationship:

$\lambda=\frac{c}{f}$

where $c=3\cdot 10^8 m/s$ is the speed of light and f is the frequency. Substituting the frequency, we find

$\lambda=\frac{3\cdot 10^8 m/s}{3.29\cdot 10^{15}Hz}=9.12\cdot 10^{-8} m=91.2 nm$

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2 years ago

The image of an object formed by plane mirror is

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Answer of your question is in this photo

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2 years ago

A slender rod of length 80.0 cm and 0.600 kg has its center of gravity at its geometrical center. But its density is not uniform

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Explanation:

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1 year ago

What type of climate would be near cold ocean currents? PLEASE HELP QUICK!!

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3 years ago