<h3><u>Answer;</u></h3>
= 20.436 seconds
<h3><u>Explanation;</u></h3>
Speed = Distance × time
Therefore;
Time = Distance/speed
Distance = 7.50 m, speed = 0.367 m/s
Time = 7.50/0.367
<u>= 20.436 seconds </u>
Whatcha need help with ????????
Answer:
2849.98 J
Explanation:
From the question,
Work done by the boy = change Potential energy of the boy + change in kinetic energy of the boy
W = ΔP + ΔK..................... Equation 1
Where W = work done by the boy, ΔP = change in potential energy of the boy, ΔK = Change in kinetic energy of the boy.
But,
ΔP = mgΔh.................... Equation 2
ΔK = 1/2mΔv²................. Equation 3
Where m = mass of the boy, Δh = change in height of the boy, Δv = change in velocity of the boy.
Substitute equation 2 and 3 into equation 1
W = mgΔh+1/2mΔv²................. Equation 4
Given: m = 72 kg, Δh = 1.61 m, Δv = 8.5-1.6 = 6.9 m/s, g = 9.8 m/s²
Substitute into equation 4
W = 72(9.8)(1.61)+1/2(72)(6.9²)
W = 1136.016+1713.96
W = 2849.98 J
The atomic number is the simply the number of protons in the atom. So in the first row with atomic number 2, the number of protons is 2.
If the atom has no charge, which I think you can assume for all of these, the number of electrons is equal to the number of protons. So the number of electrons is also 2.
The number of neutrons (which are the particles with no charge in the nucleus) is simply the mass number minus the atomic number i.e. 4 - 2 = 2.
The isotopic symbol is the symbol which is found on the periodic table of elements. There are 2 numbers associated which each element on the table. The larger is the mass number and the smaller is the atomic number. The atomic number or number of protons is what identifies the element. Looking at the periodic table ( https://sciencenotes.org/wp-content/uploads/2015/01/PeriodicTableOfTheElementsBW.pdf or https://simple.wikipedia.org/wiki/Periodic_table_(big) ), it can be seen that the element on the first row above with an atomic number of 2 is Helium with a symbol He. The number that is included with the name is simply the mass number which is 4 in this case, which tells us that this type of helium has 2 neutrons.
Another type (or isotope) of helium is Helium-3 which has one neutron.
Try the next row and post back if you have trouble with it
