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valentina_108 [34]
3 years ago
9

A moving freight car collides with an identical one that is at rest. If momentum is conserved, what happens to the second car af

ter the collision? It attains the same speed as the first car. It moves at half the speed of the first car. It moves at twice the speed of the first car.
Physics
1 answer:
yKpoI14uk [10]3 years ago
4 0

For all elastic collisions we have

e = \frac{v_2 - v_1}{u_1 - u_2}

e = 1 = \frac{v_2 - v_1}{u_1 - u_2}

v_2 - v_1 = u - 0

also by momentum conservation we will have

m_1 u_1 + m_2 u_2 = m_1 v_1 + m_2 v_2

since two cars are identical so we know that

m_1 = m_2 = m

u + 0 = v_1 + v_2

now by solving two equations we will have

v_2 = u

v_1 = 0

so the correct answer must be

It attains the same speed as the first car.

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Write down the conservation of momentum?​
otez555 [7]
Law of conservation of momentum states that when two objects collide with each other , the sum of their linear momentum always remains same or we can say conserved and is not effected by any action, reaction only in case is no external unbalanced force is applied on the bodies.
Let,
m
A
​
= Mass of ball A
m
B
​
= Mass of ball B
u
A
​
= initial velocity of ball A
u
B
​
= initial velocity of ball B
v
A
​
= Velocity after the collision of ball A
v
B
​
= Velocity after the collision of ball B
F
ab
​
= Force exerted by A on B
F
ba
​
= Force exerted by B on A
Now,
Change in the momentum of A= momentum of A after the collision - the momentum of A before the collision
= m
A
​
v
A
​
−m
A
​
u
A
​

Rate of change of momentum A= Change in momentum of A/ time taken
=
t
m
A
​
v
A
​
−m
A
​
u
A
​

​

Force exerted by B on A (F
ba
​
);
F
ba
​
=
t
m
A
​
v
A
​
−m
A
​
u
A
​

​
........ [i]
In the same way,
Rate of change of momentum of B=
t
m
b
​
v
B
​
−m
B
​
u
B
​

​

Force exerted by A on B (F
ab
​
)=
F
ab
​
=
t
m
B
​
v
B
​
−m
B
​
u
B
​

​
.......... [ii]
Newton's third law of motion states that every action has an equal and opposite reaction, then,
F
a
​
b=−F
b
​
a [ ' -- ' sign is used to indicate that 1 object is moving in opposite direction after collision]

Using [i] and [ii] , we have
t
m
B
​
v
B
​
−m
B
​
u
B
​

​
=−
t
m
A
​
v
A
​
−m
A
​
u
A
​

​

m
B
​
v
B
​
−m
B
​
u
B
​
=−m
A
​
v
A
​
+m
A
​
u
A
​

Finally we get,
m
B
​
v
B
​
+m
A
​
v
A
​
=m
B
​
u
B
​
+m
A
​
u
A
​

This is the derivation of conservation of linear momentum.
5 0
3 years ago
The SI system uses three base units. Question 6 options: True False
GalinKa [24]

Answer:

The answer is false

Explanation:

Though the mostly used SI unit of measurement or the most popular units are the

Length,

Time and

Mass

i.e meter (m), seconds (s), kilogram (kg)

Aside all the above stated units for measurements there are other four basic units which are itemized  bellow.

they are

1. Amount of substance - mole (mole)

2. Electric current - ampere (A)

3. Temperature - kelvin (K)

4. Luminous intensity - candela (cd)

6 0
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Flura [38]

To solve the problem it is necessary to refer to the definition of entropy.

Entropy is defined aso

\Delta S = \frac{\Delta Q}{T}

Where,

\Delta Q = Heat exchange

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Since the heat exchange is conserved and it is an isothermal process where the temperature remains constant the change in entropy remains the same, ie \Delta S = 0 (Reamins same)

Therefore the correct answer is C.

8 0
4 years ago
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kolbaska11 [484]

The fundamental mode of vibration of a wave is defined as that which has the LOWEST frequency  

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The earth exerts the necessary centripetal force on an orbiting satellite to keep it moving in a circle at constant speed. Which
jenyasd209 [6]

Answer:

E) The centripetal force is always perpendicular to the velocity.

Explanation:

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8 0
4 years ago
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