The total momentum before a collision is equal to the total momentum after the collision if no external forces act on the system.
Hope this helps
For the part a) we need only the momentum of the box and we have the data to find it.
Momentum is given by,

where clearly, p is the momentum, m the mass of the box and v is the velocity.
Substituting,

For part b) we need an analysis of the situation. We understand that the box on a surface that has no friction will continue to rotate at the same speed previously defined. The box can only stop with friction, so,

<em>It is the same that part a)</em>
Answer: So, I looked at it to see what was the correct one, and the correct answer is Cool air near surface forms high-pressure areas, warm air forms low pressure areas. I hope this helps :D :)
Explanation:
Answer:
method I = 88 chairs
method II = 62 chairs
Explanation:
This problem can be modeled by a system of two linear equations.
Define x as the number of chairs refinished by method I and y by method II
The sum of hours spent on both methods should equal 199 and the sum of total material cost should equal $1226, therefore:


Multiplying the first equation by -18 and adding it to the second equation we can solve for the value of y:

We can now apply the value of y found to the first equation and solve for x:

Therefore, they should refinish 88 chairs with method I and 62 chairs with method II