Answer:
false
Explanation:
Understand Newton’s first law of motion. Experience suggests that an object at rest will remain at rest if left alone, and that an object in motion tends to slow down and stop unless some effort is made to keep it moving. An object will go on forever if there were no forces to act upon it. In space, a rocket will go forever at the speed it projects.
Answer:
v = a/√(2h/g) m/s
Explanation:
Lets say the distance away from the cliff is a.
then, a = v t
where v is velocity with which it was thrown and t is time taken to fall.
Using equations of motion, we can also say that
h=1/2gt^2
where h is the height of the cliff
Thus, t^2 = 2h/g and t = √(2h/g)
Thus, v = a/√(2h/g).
the vehicle was pushed off the cliff with the velocity , v = a/√(2h/g). m/s
Answer:
- 4.2 kJ
Explanation:
We shall find out the initial temperature of the gas
PV / T = n R
20 X 10³ X .26 / T = 9 X 8.3
T = 69.6 K
Since the pressure of gas is constant
V / T = constant
V₁ / T₁ = V₂ / T₂
.26 / 69.6 = .12 / T₂
T₂ = 32.12 K
gas is cooling so there will be decrease in internal energy
Change in temperature = 69.6 - 32.12
= 37.48 K.
decrease in internal energy
= - n Cv x fall in temperature
= - 9 x 1.5 x 8.31 x 37.48 ( Cv = 1.5 R given )
= - 4.2 kJ .
Answer:
Elements- made of one type of atom
Can not be broken down
Compounds
Represented by formulas
Can be chemically broken down
Made of two or more types of atoms
Explanation:
An element is a chemical substance which cannot be further broken down into other chemical substances. An element is composed of only one type of atom. Examples of elements include, sodium, magnesium, gold, silver etc.
Compounds are formed when one or more elements combine in a definite ratio. Compounds are represented by chemical formulas which show the number of combining atoms e.g CaCO3, HF, etc. Some compounds can be broken down chemically.