Answer:
The particle’s velocity is -16.9 m/s.
Explanation:
Given that,
Initial velocity of particle in negative x direction= 4.91 m/s
Time = 12.9 s
Final velocity of particle in positive x direction= 7.12 m/s
Before 12.4 sec,
Velocity of particle in negative x direction= 5.32 m/s
We need to calculate the acceleration
Using equation of motion


Where, v = final velocity
u = initial velocity
t = time
Put the value into the equation


We need to calculate the initial speed of the particle
Using equation of motion again


Put the value into the formula


Hence, The particle’s velocity is -16.9 m/s.
Answer:
The maximum length during the motion is 
Explanation:
From the question we are told that
The mass is 
The vertical spring length is 
The unstretched length is 
The initial speed is 
The new length of the spring 
The spring constant k is mathematically represented as

Where F is the force applied 
y is the difference in weight which is 
The negative sign is because the displacement of the spring (i.e its extension occurs against the force F)
Now substituting values accordingly


The elastic potential energy is given as 
where D is this the is the displacement
Since Energy is conserved the total elastic potential energy would be

Substituting value accordingly




So to obtain total length we would add the unstretched length
So we have

Answer:
B. a piece of paper being torn
Explanation:
A chemical change is one that cannot be reversed. This means the original properties of the substance or object cannot be restored.
If you cook a raw egg, it would turn into a boiled egg (or a poached egg, however it is being cooked). The reaction is irreversible, so you cannot turn the cooked egg back into a raw egg - it is basically impossible to 'uncook' an already cooked egg.
When you toast a piece of bread, it turns into toast. You can't 'untoast' it back into bread. The chemical changes have already occurred and cannot be undone.
If you tear a piece of paper, it is still paper. You are only ripping it, not changing anything about it. You could simply tape the torn bit back to the original bit, or glue it - either way, it is still paper and nothing has occurred to drastically change the physical state of it.
Therefore, B is not a chemical change.
Answer:
a) The plasma membrane is called a selectively permeable membrane as it permits the movement of only certain molecules in and out of the cells. ... It allows hydrophobic molecules and small polar molecules diffuse through the lipid layer, but does not allow ions and large polar molecules cannot diffuse through the membrane
b) Plastids are present in the cells of plants. They are characterised by the presence of pigments. ... Chloroplasts contain chlorophyll and carotenoid pigments responsible for capturing the light energy that is necessary for photosynthesis. The chloroplasts are therefore known as the kitchen of the cell.
c) Lysosomes are known as the suicidal bag of the cell because it is capable of destroying its own cell in which it is present. It contains many hydrolytic enzymes which are responsible for the destruction process. This happens when either the cell is aged or gets infected by foreign agents like any bacteria or virus.
d) Mitochondria are often called the “powerhouses” or “energy factories” of a cell because they are responsible for making adenosine triphosphate (ATP), the cell's main energy-carrying molecule. ... In mitochondria, this process uses oxygen and produces carbon dioxide as a waste product.
e) In Hydra, the cells are arranged in two germinal layers—outer ectoderm and inner endoderm. Between these two layers is a layer of undifferentiated cells called mesoglea. Such kind of pattern of embryonic layers is seen in diploblastic animals. Hence, Hydra is a diploblastic animal.
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Answer:
A lone neutron spontaneously decays into a proton plus an electron.
Explanation:
In an atom, nuclei contain protons and neutrons, which are the fundamental particles of an atom. Neutrons are stable and uncharged particles inside a nucleus.
For 15 times during its lifetime, a free neutron decays and breaks down into more smaller particles.This breakdown causes problems in nuclear reactors, as they start decaying and emit radiations of different wavelengths.
A neutron undergoes the decaying process to produce an electron, a proton, and energy.
The reaction of neutron decay:
n0 → p+ + e− + νe