Using the conservation of momentum,
ma*va1 + mb*vb1 = ma*va2 + mb*vb2
Let:
ma = mass of the ball
va = velocity of the ball
mb = mass of the man
vb = velocity of the man
The subscript 1 is known as initials while 2 is for finals.
Before the man throws the ball, he starts at rest, meaning the initial velocity of the ball and the initial velocity of the man are zero. So
0 = ma*va2 + mb*vb2
Given ma = 10 kg; va = 20 m/s; mb = 90 kg; vb is unknown, therefore
-(mb*vb2) = ma*va2
vb2 = -(ma*va2)/mb2 = -(10*20)/90 = -2.22 m/s
Notice that his velocity is negative because when he finally throws the ball (say to the right), he moves at the opposite direction (that is to the left) on which he stands on the frictionless surface.
The word 'apparent' mean in apparent visual magnitude is, how bright the star appears when viewed from Earth.
What is visual magnitude?
The brightness of a celestial body is determined by eye estimation with or without optical aid or by other instrumentation equivalent to the eye in spectral sensitivity.
Apparent magnitude:
- Apparent magnitude is a measure of how bright the star appears when viewed from Earth.
- It is a measure of the brightness of a star or other astronomical object observed from Earth.
- An object's apparent magnitude depends on its intrinsic luminosity and its distance from Earth.
Hence,
The word 'apparent' mean in apparent visual magnitude is, how bright the star appears when viewed from Earth.
Learn more about visual magnitude here:
<u>brainly.com/question/14782876</u>
#SPJ4
The numbers in front of a compound is called a subscript. It shows how many atoms of that specific element it is next two that is involved in the reaction or is in that compound.
The answer is then D.
Coefficient is found behind the compounds, the charges are written above.