Forces are considered balanced when all of the combined forces lead to no change in the motion of the object. For example, when a book is sitting on a table, the force of gravity is pushing downward and the normal force is pushing upward with exactly the same amount of force. Since they are equal and opposite forces, the book does not move.
Unbalanced forces exist when there are unequal forces acting upon the object, which leads to a change in the state of motion. Unbalanced forces can lead to a change in direction, a change in speed, or both a change in direction and in speed.
The answer for question 1 is A.
The answer for question 2 is C
The correct answer is good architecture is
Answer:
the Earth-Sun distance.
Explanation:
To measure parallax the base line distance that we need to know is the Earth-Sun distance. This distance is called 1 astronomical unit. This distance is 1.496×10^8 Km. So, this base line distance is necessary for the second link parallax.
Answer:
Having a bigger angle above the horizontal
Explanation:
Applying the energy conservation theorem:

The kinetic energy is reduced because of the work done by the friction force.
The friction force is given by:

so the friction force depends on the Normal force, because the slide has an angle the normal force is given by:

So when the angle of the slide is bigger, the friction force decreases, for example:
for 45 degrees:

for 75 degrees:

as you can see if the angle is bigger above the horizontal, the friction force is reduced and so the work done by that force. We didn't have to change the height of the slide, so the potential gravitational energy remains the same.