Answer:
Natural selection is a simple mechanism that causes populations of living things to change over time. Organisms that are more adapted to their environment are more likely to survive and pass on the genes that aided their success.
Answer:

Explanation:
Let say the empty wagon has mass "M"
now by newton's II Law we will have

now it is given that empty wagon is pulled with acceleration 1.4 m/s/s
now we will have

now a child of mass three times the mass of wagon is sitting on the empty wagon
so here we have


so we have

At First, there is chemical Energy( in your muscels) which is Used to Push down the spring. This Energy becomes the Energy of the spring, which increases until you stop pushing. If you Put your hand away, the Energy of the spring will become kinetic energ. This Energy is at the highest Level the Moment the book ist Leaving the spring. Afterwards, the kinetic Energy decreases while the Gravitational Potential Energy increases.
Answer:
= 1000 hours
Explanation:
Earth's circumference is 10⁴ mile
speed of a sailboat is 10¹ mile/hour
distance = speed × time
10⁴ = 10¹ × t
t = 10⁴ / 10¹
t = 10³
= 1000 hours