For this problem the figure below shows the representation of a student who pulls on a 20kg box. We know this variables:
Weight of the box = 20kg
Force used by the student to pull on the box = 50N (This is the tension T)
Angle relative to the horizontal = 45 degrees
Aceleration of the box =
The figure also shows the Free-Body diagram, Applying Newton's Second Law we can find the equation for this diagram, related to the x-axis as:
Isolating
:
<span>That is the friction force on the box.</span>
Answer:
877
Explanation:
P1 = 150 atm
V1 = 0.12 m^3
P2 = 1.2 atm
V2 = ?
radius of each balloon, r = 0.16 m
Volume of each balloon,
V2 = 0.0171 m^3
Let the number of balloons be N.
So,
P1 x V1 = N x P2 x V2
150 x 0.12 = N x 1.2 x 0.0171
N = 877.19
So, the number of balloons be 877.
Well we can't see the picture that the teacher has, and we have to figure out what's in the picture from some clues in the answer choices. The picture seems to show an atom with 3 protons and 3 neutrons in the nucleus, and 3 electrons whizzing around the nucleus.
If that's what's in the picture, then Mike is correct (first choice), because the atomic number shows the number of protons in all atoms. There are 3 protons and the atomic number of lithium is 3.
Second choice . . . False, because electrons are not involved in the atomic mass.
Third and fourth choices . . . both false; sadly, Joan is woefully unclear on the concepts.