We will apply the conservation of linear momentum to answer this question.
Whenever there is an interaction between any number of objects, the total momentum before is the same as the total momentum after. For simplicity's sake we mostly use this equation to keep track of the momenta of two objects before and after a collision:
m₁v₁ + m₂v₂ = m₁v₁' + m₂v₂'
Note that v₁ and v₁' is the velocity of m₁ before and after the collision.
Let's choose m₁ and v₁ to represent the bullet's mass and velocity.
m₂ and v₂ represents the wood block's mass and velocity.
The bullet and wood will stick together after the collision, so their final velocities will be the same. v₁' = v₂'. We can simplify the equation by replacing these terms with a single term v'
m₁v₁ + m₂v₂ = m₁v' + m₂v'
m₁v₁ + m₂v₂ = (m₁+m₂)v'
Let's assume the wood block is initially at rest, so v₂ is 0. We can use this to further simplify the equation.
m₁v₁ = (m₁+m₂)v'
Here are the given values:
m₁ = 0.005kg
v₁ = 500m/s
m₂ = 5kg
Plug in the values and solve for v'
0.005×500 = (0.005+5)v'
v' = 0.4995m/s
v' ≅ 0.5m/s
Answer: 14.28 m/s
Explanation:
Assuming the girl is spinning with <u>uniform circular motion</u>, her centripetal acceleration 
is given by the following equation:
(1)
Where:
is the <u>centripetal acceleration</u>
is the<u> tangential speed</u>
is the <u>radius</u> of the circle
Isolating from (1):
(2)
<u />
Finally:
This is the girl's tangential speed
Lightning is a naturally occurring electrostatic discharge during which two electrically charged regions in the atmosphere or ground temporarily equalize themselves, causing the instantaneous release of as much as one gigajoule of energy.
Answer: a) - 437.8° F, b) - 261°c.
Explanation: a) the kelvin and Fahrenheit temperature scale are related by the formulae below.
5 (°F - 32) = 9 (k - 273)
Where °F = temperature in Fahrenheit and k = temperature in kelvin.
For question A, k = 12.0, by substituting to have the value for °F, we have
5(°F - 32) = 9 ( 12 - 273)
5(°F - 32) = 9(-261)
5(°F - 32) = - 2349
°F - 32 = - 2349/5
°F - 32 = - 469.8
°F = - 469.8 + 32
°F = - 437.8
Question B
The centigrade and kelvin scale are related by the formulae below
°c = k - 273
Where °c = temperature in centigrade and k = temperature in kelvin =12
°c = 12 - 273
°c = - 261
Answer:
r = 5,085 m
Explanation:
The force exerted by on the surface of the Earth on an electron is its weight
W = F = 9.11 10⁻³¹ 9.8
W = 8.9 10⁻³⁰ N
The electric force between an electron and a proton is given by Coulomb's Law
Fe = k q₁ q₂ / r²
Fe = - k q² / r²
They ask us that W = Fe
W = k q² / r²
r = √ k q² / W
Let's calculate
r = √ 8.99 10⁹ (1.6 10⁻¹⁹)² /8.9 10⁻³⁰
r = √ 25.86
r = 5,085 m
Let's look for the relationship of this distance with the harmonic distance
R / R_atomic = 5,085 / 10⁻¹⁰
R / R_Atomic = 5 10¹⁰
We see that this distance is 10¹⁰ times the interatomic distance, so the gravitational attraction force is very small at atomic scale
