A campfire being lighted and plants converting carbon-dioxide and water into glucose and oxygen are both forms of chemical change.
Therefore, the answer is:
B. Both are examples of chemical change.
Answer:
There is an inward force acting on the can
Explanation:
This inward force is known as Centripetal force and it is responsible for making the can whirl on the end of a string in circle and it is also directed towards the center around which the can is moving.
1) weight of the box: 980 N
The weight of the box is given by:

where m=100.0 kg is the mass of the box, and
is the acceleration due to gravity. Substituting in the formula, we find

2) Normal force: 630 N
The magnitude of the normal force is equal to the component of the weight which is perpendicular to the ramp, which is given by

where W is the weight of the box, calculated in the previous step, and
is the angle of the ramp. Substituting, we find

3) Acceleration: 
The acceleration of the box along the ramp is equal to the component of the acceleration of gravity parallel to the ramp, which is given by

Substituting, we find

Answer:
The first interval is walked slowly, this is a straight line with a small slope
Second interval stops, which gives a horizontal line, indicating the same position
Third interval, walk back, straight downhill
Explanation:
In this problem we have a uniform movement, this means that the acceleration in each intervals
x = v t
The first interval is walked slowly, this is a straight line with a small slope
Second interval stops, which gives a horizontal line, indicating the same position
Third interval, walk back, straight downhill
If the book is placed in the middle, the forces acting on <em>p</em> and <em>q</em> is 5N. If the book is moved 50 cm from <em>q</em>, the forces at <em>p</em> and <em>q</em> can be solved by doing a moment balance
<u>With </u><u><em>p</em></u><u> as the pivot;</u>
Fq (2 m) = 10 N (0.5 m)
Fq = 2.5 N
Fp = 10 N - 2.5 N = 7.5 N