Answer:
a. Temperatures increase can change a solid to a liquid, but cannot change a liquid to a solid
b. The particles in a solid are much closer together than the particles in a liquid.
Explanation:
Any material expands when heated and contracts when cooled. So, when a body is heated to a particular temperature, it starts melting and changes into a liquid.
As the material expands the distance between the atoms or molecules increases and it will become a liquid. So it can move around the material. It doesn't become solid on further heating. But water is an exception where it contracts when heated from 0° to 4° C.
In solids, these atoms or molecules are closely packed. It is rigidly fixed.
The solid, as well as the liquid, has a definite volume, but the liquid does not have a definite shape.
Answer:
40 N
Explanation:
We first need to calculate the acceleration of the tron ball.
Since acceleration, a = (v - u)/t where u = initial velocity of iron ball = 17m/s, v = final velocity of iron ball = 27m/s and t = time taken for the change in velocity = 5 s.
So, a = (v - u)/t
= (27 m/s - 17 m/s)/5 s
= 10 m/s ÷ 5 s
= 2 m/s²
We know force on iron ball, F = ma where m = mass of iron ball = 20 kg and a = acceleration = 2 m/s²
So, F = ma
= 20 kg × 2 m/s²
= 40 kgm/s²
= 40 N
So, the magnitude of the force on the iron ball is 40 N.
I think the correct answer is C
A. Scientific Law. The mathematics surrounding the acceleration due to gravity is a law. It is calculated from the universal law of gravity. However, the explanation of the idea of gravity is a theory. This falls back to the idea that science is about disproving ideas that we currently believe, rather than proving ideas are correct. Unless we can disprove an idea, we have to accept the possibility that it is true; the more trials we have of being unable to disprove something, the more accepted it will be. Yet, no idea can be without doubt and certainty be accepted for what it is. So, to sum it up, scientific laws are factual descriptions (by formula or word) of phenomenon which always occur given specific conditions. On the other hand, scientific theories are explanations of the causes underlying these phenomena, the explanation formulated in such a way that they can be disproven.
