Answer:
Explanation:
To find the amplitude of the sound, we must first determine the wavelength and the phase difference between the two speakers.
For the wavelength;
Recall that, the separation between two successive max. and min. intensity points are 
Thus; for both speakers; the wavelength of the sound is:


λ = 80 cm
The relation between the path difference(Δx) and the phase difference(Δ∅) is:

where;
Δx = 10 cm
λ = 80 cm
Δ∅ = π rad
∴







Suppose both speakers are placed side-by-side, then the path difference between the two speakers is: Δx = 0 cm
Thus, we have:



∴
The amplitude of the sound wave if the two speakers are placed side-by-side is:



A = 0.765a
Explanation:
By Hooke's Law,
F=kx
The only force acting here is weight, and x is the extension of the string (you need to convert this to mm) so
mg=kx
(0.15)(9.81)=k ((420-300)x10^-3)
Then just solve this equation.
Answer:
The question clearly describes the circular motion.
The circular motion equation is

The path of the particle is circular.
Explanation:
In circular motion, the radial acceleration is always towards the center and constant in magnitude. Furthermore, the velocity of the circular motion is always tangential to the circle, that is it is always perpendicular to the radius, hence the acceleration.
Answer:
Conservation of momentum.
Momentum is zero after collision, no direction or speed.
Explanation: