Answer:
240m/s
Explanation:
The equation to calculate is wavelength= velocity/ frequency so to find the velocity you would have to multiply frequency by wavelength.
Why do transformers hum? Transformer noise is caused by a phenomenon which causes a piece of magnetic sheet steel to extend itself when magnetized. When the magnetization is taken away, it goes back to its original condition. This phenomenon is scientifically referred to as magnetostriction.
By looking at the acceleration of the object.
In fact, Netwon's second law states that the resultant of the forces acting on an object is equal to the product between the mass m of the object and its acceleration:

So, when static friction is acting on the object, if the object is still not moving we know that all the forces are balanced: in fact, since the object is stationary, its acceleration is zero, and so the resultant of the forces (left term in the formula) must be zero as well (i.e. the forces are balanced).
I believe the answer is A Voltage available to each light remains constant regardless of the number of lights that are on.
Agree cause it is that persons environment not the law or the law makers