Why is the mass of an atom's electrons not included in the atom's mass number?

Physics

1 answer:

Katen [24]3 years ago

8 0

Answer: A: the electrons move so fast that their mass cannot be measured

Explanation: because they are so fast scientist and other people cannot measure them

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A 62.2-kg person, running horizontally with a velocity of 3.80 m/s, jumps onto a 19.7-kg sled that is initially at rest. (a) Ign

jek_recluse [69]

Answer:

a) $v = 2.886\,\frac{m}{s}$ , b) $\mu_{k} = 0.014$

Explanation:

a) The final speed is determined by the Principle of Momentum Conservation:

$(62.2\,kg)\cdot (3.80\,\frac{m}{s} ) = (81.9\,kg)\cdot v$

$v = 2.886\,\frac{m}{s}$

b) The deceleration experimented by the system person-sled is:

$a = \frac{\left(0\,\frac{m}{s} \right)^{2}-\left(2.886\,\frac{m}{s} \right)^{2}}{2\cdot (30\,m)}$

$a = -0.139\,\frac{m}{s^{2}}$

By using the Newton's Laws, the only force acting on the motion of the system is the friction between snow and sled. The kinetic coefficient of friction is:

$-\mu_{k}\cdot m\cdot g = m\cdot a$

$\mu_{k} = -\frac{a}{g}$

$\mu_{k} = -\frac{\left(-0.139\,\frac{m}{s^{2}} \right)}{9.807\,\frac{m}{s^{2}} }$

$\mu_{k} = 0.014$

3 0

4 years ago

Anettt [7]

Proton: Its electrical charge is +1, its mass is 1, it's found in the nucleus

Neutron: Its electrical charge is 0, its mass is 1, it's found in the nucleus

Electron: Its electrical charge is -1, its mass is negligible, it's found outside the nucleus

Explanation:

Atoms consist of three types of particles:

Proton: the proton is found in the nucleus of the atom, and it has a positive electric charge, equal to $+1.6\cdot 10^{-19}C$ (expressed in units of fundamental charge, it has a charge of +1). Its mass is $1.67\cdot 10^{-27}kg$ , while its mass expressed in atomic mass units is 1 a.m.u
Neutron: the neutron is also found in the nucleus of the atom, and it has no electric charge. Its mass is similar to the mass of the proton (slightly larger), and neutrons and protons are held together in the nucleus by the presence of the strong nuclear force
Electron: the electron orbits around the nucleus, far away from it. It has negative electric charge, opposite to that of the proton ( $-1.6\cdot 10^{-19}C$ , or -1 in units of fundamental charge). Its mass is much lower than that of the proton, approximately 1800 times smaller, so it can be considered as negligible.