Answer:
16.935 N
Explanation:
In order to make the box start moving, the level force applied on the box (F) must be greater than the force of static friction that keeps the box at rest, which is equal to
where
is the coefficient of static friction
(mg) = 30 N is the weight of the box
Therefore, the condition for F must be:
So, the applied force must be greater than this value.
Answer:
The type of interference the person perceives is a Constructive Interference
Explanation:
Before we solve the problem we need to clarify some concepts:
There are two types of Interference, the Constructive and the Destructive interference
The Constructive Interference happens if the difference between the waves movement is equal to an even semi-wavelength number
The Destructive Interference is the opposite than the Constructive Interference, it happens if the difference between the waves movement is equal to an odd semi-wavelength number
Taking the above into account let´s proceed to solve the problem.
First, we will need to find how much the wavelength is (we will call it l), we know the frequency f=200Hz, we also know the speed of sound is v=330m/s. We will use the next equation:
then we get that
In order to find the semi-wavelength we must divide by 2 the previous result, in this case the semi-wavelength will be:
Now, we find the difference between the waves movement, which is the difference between both distances, this difference will be called d and we will find it this way:
then d=3.3m
After this, we will do a relation between the distance and the semi-wavelength in order to find what type of interference the person perceives, this way:
then, we have a relation equals to 4. As it´s an even number, we determine the interference is a Constructive Interference