I believe d all of the above
Answer:
6.0 N
Explanation:
The strength of a force is expressed as the magnitude of the force in Newton.
The formula to apply here is :
Force= mass * acceleration
F=ma
Mass, m = 4 kg
Acceleration = 1.5 m/s²
Force= 4 *1.5 = 6.0 N
Angry sound level = 70 db
Soothing sound level = 50 db
Frequency, f = 500 Hz
Assuming speed of sound = 345 m/s
Density (assumed) = 1.21 kg/m^3
Reference sound intensity, Io = 1*10^-12 w/m^2
Part (a): Initial sound intensity (angry sound)
10log (I/Io) = Sound level
Therefore,
For Ia = 70 db
Ia/(1*10^-12) = 10^(70/10)
Ia = 10^(70/10)*10^-12 = 1*10^-5 W/m^2
Part (b): Final sound intensity (soothing sound)
Is = 50 db
Therefore,
Is = 10^(50/10)*10^-12 = 18*10^-7 W/m^2
Part (c): Initial sound wave amplitude
Now,
I (W/m^2) = 0.5*A^2*density*velocity*4*π^2*frequency^2
Making A the subject;
A = Sqrt [I/(0.5*density*velocity*4π^2*frequency^2)]
Substituting;
A_initial = Sqrt [(1*10^-5)/(0.5*1.21*345*4π^2*500^2)] = 6.97*10^-8 m = 69.7 nm
Part (d): Final sound wave amplitude
A_final = Sqrt [(1*10^-7)/(0.5*1.21*345*4π^2*500^2)] = 6.97*10^-9 m = 6.97 nm
Answer:
- 1.42m/s²
Explanation:
Acceleration is defined as the change in velocity of a body with respect to time.
Acceleration = change in velocity/time
Change in velocity = final velocity - initial velocity
Acceleration = final velocity - initial velocity/time
Since she slows her car from 14.0 to 5.5m/s in 6seconds,
Initial velocity = 14m/s
Final velocity = 5.5m/s
Time = 6seconds
Substituting in the given formula, we will have
Acceleration = 5.5 - 14/6
Acceleration = - 8.5/6
Acceleration = - 1.42m/s²
The negative acceleration shows that the car decelerates.
