Physical changes are those which do not affect the chemical properties of a substance. For example, when a paper is cut, the two pieces obtained are still paper. The chemical properties have not changed. Only, physically when one piece is cut to two. A chemical change occurs when the chemical properties change and a new substance with different chemical properties is obtained. For example, when the paper is burnt, it turns to ashes. Hence, this is a chemical change.
When a substance undergoes a physical change, the physical properties of the substance changes like the state (solid to liquid during melting), shape, size, volume etc. Many physical changes are reversible whereas, in general many chemical changes are irreversible.
Answer:
A
Explanation:
I'm pretty sure it's A because when you look up the properties of alkali metal it states stuff about its melting points and what to expect. (correct me if I'm wrong but I had this same question on a test and I'm sure this is the answer lol)
I'm not sure of the numbers sense I dont have a calculator right now. The formula is 1/2*M*V^2.
Team work and a can do attitude is very important when being a team worker, as well as being open minded!
I hope this helps!
Answer:
49 m/s
Explanation:
This is the question from the document:
1. A bag dropped from a helicopter falls with an acceleration of 9.8m/s2. What is its velocity after 5s?
We can find the answer by using the equation a = (v-u) / t
Acceleration a = 9.81m/s2
initial velocity u = 0 m/s (the bag is only dropped, so there's no initial velocity already existing)
time t= 5s
final velocity v = unknown
9.8 = (v -0) / 5
v - 0 = 9.8x5
v = 49 m/s
