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2 years ago

What is atomic theory and how has it changed over time?

2 answers:

6 0

<span>In chemistry and physics, the atomic theory explains how our understanding of the atom has changed over time. Atoms were once thought to be the smallest pieces of matter. The first idea of the atom came from the Greek philosopher Democritus. Hope I helped!!</span>

Snezhnost [94]2 years ago

5 0

Atomic theory<span> is a scientific </span>theory<span> of the nature of matter. </span>The atomic theory has changed over time as new technologies have become available. Scientific knowledge builds on past research and experimentation. Democritus, a philosopher in ancient Greece, began the search for a description of matter. ... He believed that the smallest possible piece of matter was indivisible.

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A 15g bullet is fired horizontally into a 3kg block of wood suspended by a long cord. Assume that the bullet remains in the bloc

Varvara68 [4.7K]

Answer:

261.3 m/s

Explanation:

Mass of bullet=m=15 g= $\frac{15}{1000}=0.015 kg$

1 kg=1000g

Mass of block=M=3 kg

d=0.086 m

Total mass =M+m=3+0.015=3.015 kg

K.E at the time strike=Gravitational potential energy at the end of swing

$\frac{1}{2}(m+M)^2V^2=(m+M)gh$

Using g= $9.8m/s^2$

Substitute the values

$\frac{1}{2}(3.015)V^2=3.015\times 9.8\times 0.086$

$V^2=\frac{2\times 3.015\times 9.8\times 0.086}{3.015}$

$V=\sqrt{2\times 3.015\times 9.8\times 0.086}}$

$V=1.3m/s$

Velocity after collision=V=1.3 m/s

Velocity of block=v'=0

Using conservation law of momentum

$mv+Mv'=(m+M)V$

Using the formula

$0.015v+3(0)=3.015(1.3)$

$0.015v=3.015(1.3)$

$v^2=\frac{3.015(1.3)}{0.015}=261.3$

$v=261.3 m/s$

5 0

3 years ago

A brick is dropped from a high scaffold. a. What is its velocity after 4.0s ?

Ilia_Sergeevich [38]

Answer:

A: 1.962

B: 3.924

Explanation:

g = G *M /R^2

g = 9.807*M/R^2 the gravitational constant of ground level on earth is about 9.807

g = 9.807*5lbs/R^2 the average brick is about 5 pounds.

g = 9.807*5*10^2. I'm assuming the height is around ten feet to help you out.

with these numbers plugged in you get an acceleration of 0.4905 a final velocity after 4 seconds 1.962. It's height fallen after 4 seconds is 3.924.

( M = whatever the brick weighs it's not specified in the question)

(R = the distance from the ground or how high the scaffold is)

(hopefully you can just plug your numbers in there hope this helps)

6 0

2 years ago

A piece of metal has attained a velocity of 107.8 m/sec after fallinf for 10 seconds what is its initial velocity

soldi70 [24.7K]

Answer:

7.8 m/s

Explanation:

Here object is falling with a gravitational acceleration there for we can take acceleration = 10 m/ s² and its constant through out the motion there for we can use motion equation

V = U + at

V - Final velocity

U - Initial velocity

a - acceleration

t - time

V=U+at

107.8=U + 10×10

= 7.8 m/s

4 0

2 years ago

Why would physics be used to study light emitted by a star?

VARVARA [1.3K]

Answer:

O D.

Explanation:

Physics has an aspect that deals with the study of energy

8 0

2 years ago

Maya made this picture to represent a chemical reaction:

Natalka [10]

The statement that best explains the type of chemical reaction represented by Maya's picture is that it is neither a synthesis reaction nor a decomposition reaction because two reactants form two products. That is option B.

<h3>What is a chemical reaction?</h3>

A chemical reaction is the combination of two elements to yield a new product through the formation of bonds.

A chemical reaction is said to be a synthesis reaction when when two different atoms or molecules interact to form a different molecule or compound.

A chemical reaction is said to be a decomposition reaction when one reactant breaks down into two or more products.

Therefore, from the picture, the chemical reaction is neither a synthesis reaction nor a decomposition reaction because two reactants form two products.

Learn more about chemical reaction here:

brainly.com/question/16416932

#SPJ1

5 0

1 year ago