Why do some coastal cities experience a moderation of temperature from water?

What contributions did J.J. Thomson make to atomic history?

luda_lava [24]

J.J. Thomson discovered electrons and noticed that an atom can be divided. Also, he concluded atoms are made of positive cores and negatively charged particles within it.

4 0

3 years ago

The platform height for Olympic divers is 10 m. A 60 kg diver steps off the platform to begin his dive.

azamat

Answer:

a) Ep = 5886[J]; b) v = 14[m/s]; c) W = 5886[J]; d) F = 1763.4[N]

Explanation:

a)

The potential energy can be found using the following expression, we will take the ground level as the reference point where the potential energy is equal to zero.

$E_{p} =m*g*h\\where:\\m = mass = 60[kg]\\g = gravity = 9.81[m/s^2]\\h = elevation = 10 [m]\\E_{p}=60*9.81*10\\E_{p}=5886[J]$

b)

Since energy is conserved, that is, potential energy is transformed into kinetic energy, the moment the harpsichord touches water, all potential energy is transformed into kinetic energy.

$E_{p} = E_{k} \\5886 =0.5*m*v^{2} \\v = \sqrt{\frac{5886}{0.5*60} }\\v = 14[m/s]$

c)

The work is equal to

W = 5886 [J]

d)

We need to use the following equation and find the deceleration of the diver at the moment when he stops his velocity is zero.

$v_{f} ^{2}= v_{o} ^{2}-2*a*d\\where:\\d = 2.5[m]\\v_{f}=0\\v_{o} =14[m/s]\\Therefore\\a = \frac{14^{2} }{2*2.5} \\a = 39.2[m/s^2]$

By performing a sum of forces equal to the product of mass by acceleration (newton's second law), we can find the force that acts to reduce the speed of the diver to zero.

m*g - F = m*a

F = m*a - m*g

F = (60*39.2) - (60*9.81)

F = 1763.4 [N]

3 0

3 years ago

A lone neutron spontaneously decays into a proton plus an _______

frosja888 [35]

Answer:

A lone neutron spontaneously decays into a proton plus an electron.

Explanation:

In an atom, nuclei contain protons and neutrons, which are the fundamental particles of an atom. Neutrons are stable and uncharged particles inside a nucleus.

For 15 times during its lifetime, a free neutron decays and breaks down into more smaller particles.This breakdown causes problems in nuclear reactors, as they start decaying and emit radiations of different wavelengths.

A neutron undergoes the decaying process to produce an electron, a proton, and energy.

The reaction of neutron decay:

n0 → p+ + e− + νe

5 0

3 years ago

Polypeptides contain _______ amino acids joined by peptide bonds.

sergiy2304 [10]

Polypeptides contain more than 10 amino acids joined by peptide bonds.

7 0

3 years ago

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In the periodic table of elements, what do all of the elements in group 2 have in common?