<em>number of waves that pass a given point in one second is called <u>frequency..</u></em>
Answer:
The mass of the box:
m = 60 kg
Explanation:
Given:
F = 150 N
g = 10 m/s²
_________
m - ?
Coefficient of friction wood on wood:
μ = 0.25
Friction force:
F₁ = μ*m*g
Newton's Third Law:
F = F₁
F = μ*m*g
The mass of the box:
m = F / ( μ*g) = 150 / (0.25*10) = 60 kg
The correct answer is the Mesosphere. <span>Mesosphere </span><span>is the layer of the Earth's atmosphere that is directly above the stratopause and directly below the mesopause.</span>
Newton's second law states that the resultant of the forces applied to an object is equal to the product between the object's mass and its acceleration:

where in our problem, m is the mass the (child+cart) and a is the acceleration of the system.
We are only concerned about what it happens on the horizontal axis, so there are two forces acting on the cart+child system: the force F of the man pushing it, and the frictional force

acting in the opposite direction. So Newton's second law can be rewritten as

or

since the frictional force is 15 N and we want to achieve an acceleration of

, we can substitute these values to find what is the force the man needs: