Answer:
1 and 3
Explanation:
<u>1 and 3 </u>
Increasing coils increases strength
COOLING the wire would increase current flow and strength of magnet
Adding an iron core will definitely increase the strength of the electromagnet
Answer:

Explanation:
The change in potential energy can be expressed as:

where K is a constant with a value of
, q1 and q2 are the charges of the proton and the electron and r is the distance between them.
The charge for the proton is
and the charge for the electron is
.
Converting r=1.0nm to m:

Replacing values:


Answer:
The final velocity of the bullet is 9 m/s.
Explanation:
We have,
Mass of a bullet is, m = 0.05 kg
Mass of wooden block is, M = 5 kg
Initial speed of bullet, v = 909 m/s
The bullet embeds itself in the block which flies off its stand. Let V is the final velocity of the bullet. The this case, momentum of the system remains conserved. So,

So, the final velocity of the bullet is 9 m/s.
Answer:
You will be able to tell whether the unknown cell is from an animal or from a plant through the knowledge of difference between plants and animal cells.
Explanation:
A cell can be defined as the simplest bit of living matter which exhibits a variety of shapes and sizes and that can exist independently.
When a slide of an unknown cell is studied under a microscope, different cell structures would be observed which would be used to conclude if the cell on the slide is a plant or animal cell.
The following features are observed in a plant cell:
--> cellulose cell wall is present
--> Chloroplast is present
--> A large central vacuole is present
--> Centriole is absent
The following features are observed in animal cell:
--> Cellulose cell wall is absent
--> Chloroplast is absent
--> Small vacuoles is present
--> Centriole is present
The difference between a plant and an animal cell can be seen from the features above and a clear knowledge of this will help the student tell whether the unknown cell is from an animal or from a plant.
A person is submerged of about 97.9%.
The average density of the human body is given as 979 kg/ m³.
<h3>Define Law of floatation.</h3>
Law of floatation can be defined as the volume of the liquid displaced when a body floats on the liquid surface is equal to the body submerged in the water.
As body has the stable equilibrium state, the buoyancy of the fluid will be equal to the weight.
Weight of the body floating = Weight of the body immersed in fluid
Law of floatation = Density of the floating object / density of fluid
As fluid is the freshwater here, the density of fluid will be 1000 kg/ m³.
= (979 kg/ m³) / ( 1000 kg/ m³)
= 97.9 %
A person is submerged when floating gently in fresh water about 97.9%.
Learn more about law of floatation,
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