Answer:
The mass of the child + skateboard is 50 kg
Explanation:
In this problem, we can apply Newton's second law:
F = ma
where
F is the net force on a system
m is the mass of the system
a is the acceleration of the system
In this problem, our system is the child + the skateboard. The net force on them is
F = 75 N
and their acceleration is
So we can re-arrange the equation above to find their combined mass:
Answer:
The frequencies are
Explanation:
From the question we are told that
The length of the ear canal is
The speed of sound is assumed to be
Now taking look at a typical ear canal we see that we assume it is a closed pipe
Now the fundamental harmonics for the pipe(ear canal) is mathematically represented as
substituting values
Also the the second harmonic for the pipe (ear canal) is mathematically represented as
substituting values
Given that sound would be loudest in the pipe at the frequency, it implies that the child will have an increased audible sensitivity at this frequencies
