which variable would be most useful in determining the number of people eligible for retirement benefits in a certain year?

A rocket is fired upwards with an acceleration of 32 m/s2 . If the 200kg rocket experiences an air resistance force of 12000N, w

shutvik [7]

Answer: 20360 N

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6 0

3 years ago

Fission and fusion reactions both involve making changes to an atom's _____.

spayn [35]

Option (A) is correct. Fission and fusion reactions both involve making changes to an atom's nuclei.

Nuclear fission is a process in which a bigger nucleus breaks into two or more smaller nuclei with the liberation of large amount of energy.

Nuclear fusion is a process in which two smaller nuclei fuse together to form a bigger nucleus. A tremendous amount of energy is released during fusion.

Thus both fission and fusion involve the changes in the nuclei of atoms. Rest of the atom like the electronic configuration etc remains same.

6 0

3 years ago

Electrons are ejected from a metallic surface with speeds of up to 4.60 3 105 m/s when light with a wavelength of 625 nm is used

Darya [45]

Complete question:

Electrons are ejected from a metallic surface with speeds ranging up to 4.60 x10⁵ m/s when light with a wavelength of 625nm is used. (a) What is the work function of the surface? (b) What is the cutoff frequency for this surface?

Answer:

Part(a) The work function of the surface is 22.177 x 10⁻²⁰ J = 1.384 eV

Part(b) The cutoff frequency for this surface is 3.347 x 10¹⁴ Hz

Explanation:

The kinetic energy (KE) of the emitted photon:

KE = 0.5mv²

m is mass of electron = 9.1 X 10⁻³¹ kg

KE = 0.5 * 9.1 X 10⁻³¹ * (460000)² = 9.628 X 10⁻²⁰ J

in eV = 9.628 X 10⁻²⁰ J x 6.242 X 10¹⁸ ev = 0.601 eV

The photon energy of the incoming radiation:

E = hf = hc/λ

c is speed of light (photon) = 3 x 10⁸

h is Planck's constant = 6.626 × 10⁻³⁴ J.s

E = (6.626 × 10⁻³⁴ *3 x 10⁸) /(625 X 10⁻⁹)

E = 31.805 X 10⁻²⁰ J

in eV = 31.805 X 10⁻²⁰ J x 6.242 X 10¹⁸ ev = 1.985 eV

Part (a) the work function of the surface

KE = hf - W

where;

W is work function

W = hf - KE

W = 31.805 X 10⁻²⁰ J - 9.628 X 10⁻²⁰ J = 22.177 x 10⁻²⁰ J

in eV = 22.177 x 10⁻²⁰ J x 6.242 X 10¹⁸ ev = 1.384 eV

Part(b) the cutoff frequency for this surface

W =hf

f = W/h

f = (22.177 x 10⁻²⁰ J)/(6.626 × 10⁻³⁴ J.s)

f = 3.347 x 10¹⁴ Hz

8 0

3 years ago

Suppose you have an object tied to a rope and are rotating it over your head in uniform circular motion. What would have to do t

Crazy boy [7]

Answer:

We must duplicate the length of the rope (R'=2R) to get

$F'=\frac{1}{2}F$

Explanation:

The equation of the centripetal force is given by:

$F_{c}=ma_{c}$

$F_{c}=m\frac{v^{2}}{R}$

Where:

R is the length of the rope

m is the mass of the object

v is the speed of the object

If we want to reduce the centripetal force in half, we can duplicate the length of the rope (R'=2R), which means:

$F'_{c}=m\frac{v^{2}}{R'}$

$F'_{c}=m\frac{v^{2}}{2R}$

$F'_{c}=\frac{1}{2}F_{c}$

I hope it helps you!

6 0

3 years ago

How did the work of Dmitri Mendeleev differ from that of John Newlands in the development of the periodic table?

Sonja [21]

B.

Both recognized that the elements have repeating properties but Mendeleev realized that there are elements yet to be discovered while Newlands tried to fit the known elements together.

3 0

3 years ago

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