Im not 100% on these but i can try
1. A compound is made up of elements and their different atoms
2.
A. salt- compound (NaCl) is two elements Na (sodium) and Cl (chloride?)
B. Nitrogen- element its on the periodic table
C. Helium- element its on the periodic table
D. Water- compound (H2O) two elements hydrogen and oxygen
3. element, compound, compound, element
Hope this helps
<span>The intermolecular attractions are the caause of attraction between the molecules of liquid water. These intermolecular bonding interactions in water is due to Hydrogen bonding. The hydrogen bonding is in between O and H atoms.</span>
Before swinging, T has only potential energy, (no speed)
Ui = mgh
Where h is the vertical displacement of T
From the laws of geometry,
cos45 = (L-h)/L
cos45 = 1-h/L
h/L = 1-cos45
h = L(1-cos45)
Therefore
Ui = mgL(1-cos45)
Proceeding the same way,
Twill raise to aheight of h' due to swing
h' = L(1-cos30)
The PE of T after swing is
Uf = mgh'
Uf = mgL(1-cos30)
Along with the PE , T has some kinetic energy results due to the moment.
Tf = 0.5*mv^2
According to the law of conservation of energy,
Ui = Uf+Tf
mgL(1-cos45) = mgL(1-cos30) + 0.5*mv^2
gL(co30-cos45) = 0.5*v^2
9.8*20*(co30-cos45) = 0.5*V^2
v = 7.89 m/s
<span>The speed f T after swing is 7.89 m/s</span>