Answer:
I. Models are always wrong unless they are proved by a theory. TRUE
II. Elements, such as lead, are made of tiny particles that mostly consist of open space. FALSE
III. The air you breathe is an example of a heterogeneous mixture. FALSE
IV. An isotope of silver-108 has 61 neutrons. TRUE
Explanation:
I. All models are wrong because in order for them to be applied to reality, certain aspects that do not fit the theory must be considered.
II. All elements are made by atoms.
III. The air is an example of a homogeneous mixture of different gases. IA homogeneous system is that material system that has the same intensive properties in any part of that system. One way to check it is by viewing it. If the different parts that make it up cannot be distinguished, it will be homogeneous.
IV. Atomic number of Silver is 47. So if its mass number is 108, it has 61 neutrons and 47 protons
Answer:
The total momentum of the system is 1.45 kg*m/s.
Explanation:
The total momentum of the system is given by:
Where:
m: is the mass
v: is the velocity
d: is for duck
b₁: is for baby duck one
b₂: is for baby duck two
b₃: is for baby duck three
Therefore, the total momentum of the system is 1.45 kg*m/s.
I hope it helps you!
Complete Question:
Given at a point. What is the force per unit area at this point acting normal to the surface with ? Are there any shear stresses acting on this surface?
Answer:
Force per unit area,
There are shear stresses acting on the surface since
Explanation:
equation of the normal,
Traction vector on n,
To get the Force per unit area acting normal to the surface, find the dot product of the traction vector and the normal.
If the shear stress, , is calculated and it is not equal to zero, this means there are shear stresses.
Since , there are shear stresses acting on the surface.
The frequency of the light observed from the Earth is
Explanation:
First of all, we start by noticing that the galaxy is receding from Earth (moving away): this means that according to the Doppler effect, the frequency of the light as seen from the Earth must be shorter than the real frequency of the light emitted by the galaxy.
Furthermore, we can quantify the change in frequency of the light using the following equation:
where
is the change in frequency
f is the real frequency
v is the velocity of recession of the galaxy (negative if the galaxy is moving away)
c is the speed of light
In this problem, we have:
Substituting and solving for , we find
And therefore, the frequency of the light observed from the Earth is
Learn more about frequency and waves:
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