Any change in velocity is called an acceleration. The rock is experiencing the gravitational force from the earth, accelerating it towards the ground.
Answer:
The value is 
Explanation:
From the question we are told that
The emitted frequency increased by 
Let assume that the initial value of the emitted frequency is

Hence new frequency will be 
Generally from Doppler shift equation we have that
![f_1 = [\frac{ v \pm v_o}{v \pm + v_s } ] f](https://tex.z-dn.net/?f=f_1%20%3D%20%20%5B%5Cfrac%7B%20v%20%5Cpm%20v_o%7D%7Bv%20%5Cpm%20%2B%20v_s%20%7D%20%5D%20f)
Here v is the speed of sound with value 
is the velocity of the sound source which is
because it started from rest
is the observer velocity So
Generally given that the observer id moving towards the source, the Doppler frequency becomes
=>
=> 
The net force on the system:
F = m₂g - m₁gsin(∅)
F = 39.5 x 9.81 - 43 x 9.81 x sin(30)
F = 176.58 N
Now, we use F = ma to find the acceleration on each mass.
F = m₁a₁
a₁ = 176.58 / 43
a₁ = 4.11 m/s²
F = m₂a₂
a₂ = 176.58 / 39.5
a₂ = 4.47 m/s²
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