Nico vibrates an object at different frequencies. At a certain frequency, the sound gets louder and then returns to the same volume when he moves to the next frequency. What is occurring when the sound gets louder?

The natural frequency of the object is changing.
The amplitude of the wave is doubling.
A standing wave is being generated.
Pitch is producing the louder sound.

Ablock of mass m = 2.5 kg is attached to a spring with spring constant k = 740 n/m. it is initially at rest on an inclined plane that is at an angle of theta= 26 with respect to the horizontal, and the coefficient of kinetic friction between the block and the plane is uk = 0.17. in the initial position, where the spring is compressed by a distance of d = 0.16 m, the mass is at its lowest position and the spring is compressed the maximum amount. take the initial gravitational energy of the block as zero. the block's initial mechanical energy is 9.472 j.b. if the spring pushes the block up the incline, what distance l in meters will the block travel before coming to rest? the spring remains attached to both the block and the fixed wall throughout its motion.