There are at least two forces on it, and there could be more.
Vertical forces:
-- gravity, directed downward
-- buoyant force, directed upward
These two forces must be exactly equal, so that the net
vertical force on the raft is zero. Otherwise, it would be
accelerating either up or down.
Horizontal forces:
We know that the net horizontal force on the raft is zero.
Otherwise, it would be accelerating horizontally.
But we don't know if there are actually no horizontal forces
at all, or a balanced group of horizontal forces, that add up
to a net force of zero.
That's the description of the SOLID phase of matter.
Answer:
» e. Electrons and protons
Explaination :
Electrons are negatively charged and protons are positively charged.
- The neutrons do not have a charge.
Answer:
A) The acceleration is zero
<em>B) The total distance is 112 m</em>
Explanation:
<u>Velocity vs Time Graph</u>
It shows the behavior of the velocity as time increases. If the velocity increases, then the acceleration is positive, if the velocity decreases, the acceleration is negative, and if the velocity is constant, then the acceleration is zero.
The graph shows a horizontal line between points A and B. It means the velocity didn't change in that interval. Thus the acceleration in that zone is zero.
A. To calculate the acceleration, we use the formula:

Let's pick the extremes of the region AB: (0,8) and (12,8). The acceleration is:

This confirms the previous conclusion.
B. The distance covered by the body can be calculated as the area behind the graph. Since the velocity behaves differently after t=12 s, we'll split the total area into a rectangle and a triangle.
Area of rectangle= base*height=12 s * 8 m/s = 96 m
Area of triangle= base*height/2 = 4 s * 8 m/s /2= 16 m
The total distance is: 96 m + 16 m = 112 m
Answer:
(a) Elongation of rod = 0.19732 mm
(b) Change in diameter = 0.00651 mm
Explanation:
Circular area at end of steel rod = pi * diameter^2 / 4

Area = 3.801 * 10^(-4) meter squared
Stress = force / area
Stress = 75000 / (3.801 * 10^-4)
Stress = 197316495 Pa OR 0.197 GPa
Modulus of elasticity = stress / strain
200 = 0.19732 / Strain
Strain = 0.0009866 (longitudinal)
(a) Strain = change in length / initial length
0.0009866 = Elongation of rod / 200
Elongation of rod = 0.19732 mm
(b) Poisson ratio = lateral strain / longitudinal strain
0.3 = lateral strain / 0.0009866
Lateral strain = 0.000296
Lateral strain = Change in diameter / original diameter
0.000296 = Change in diameter / 22
Change in diameter = 0.00651 mm