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:
The force will be 54.0 units
Explanation:
The magnitude of the electrostatic force between two charged objects is given by Coulomb's Law:

where
k is Coulomb's constant
q1, q2 are the magnitude of the two charges
r is the separation between the two charges
From the equation, we see that the magnitude of the force is directly proportional to the charge of object 2:

In this problem, the initial force between the two objects is
F = 18.0 N
And so, when the charge on object 2 is tripled,

The new electrostatic force will be

So, the force will also triple: since the original force was 18.0 units, the new force will be

It always has changing velocity