The function x = (5.2 m) cos[(5πrad/s)t + π/5 rad] gives the simple harmonic motion of a body. At t = 5.3 s, what are the (a) displacement, (b) velocity, (c) acceleration, and (d) phase of the motion? Also, what are the (e) frequency and (f) period of the motion?

Respuesta :

Answer:

(a) Displacement = - 3.0576 m

(b) Velocity  [tex]=-66.48[/tex] m/s

(c)Acceleration   = -753.39 m²/s

(d)The phase motion is 26.7 [tex]\pi[/tex].

(e)Frequency =2.5 Hz.

(f)Time period =0.4 s

Explanation:

Given function is

[tex]x= (5.2 m)cos[ (5\pi \ rad/s)t+ \frac\pi5][/tex]

(a)

The displacement includes the parameter t, so,at time t=5.3 s

[tex]x|_{t=5.3}= (5.2 m)cos[ (5\pi \ rad/s)5.3+ \frac\pi5][/tex]

           [tex]= (5.2 m)cos[ 26.5\pi+ \frac\pi5][/tex]

           =(5.2)(-0.588)m

           = - 3.0576 m

(b)

[tex]x= (5.2 m)cos[ (5\pi \ rad/s)t+ \frac\pi5][/tex]

To find the velocity of simple harmonic motion, we need to find out the first order derivative of the function.

[tex]v=\frac{dx}{dt}[/tex]

 [tex]=\frac{d}{dt} (5.2 m)cos[ (5\pi \ rad/s)t+ \frac\pi5][/tex]

  [tex]= (5.2 m)(-5\pi)sin[ (5\pi \ rad/s)t+ \frac\pi5][/tex]

  [tex]= -26\pi sin[ (5\pi \ rad/s)t+ \frac\pi5][/tex]

Now we can plug our value t=5.3 into the above equation

[tex]v= -26\pi sin[ (5\pi \ rad/s)5.3\ s+ \frac\pi5][/tex]

 [tex]=-66.48[/tex] m/s

(c)

To find the acceleration of simple harmonic motion, we need to find out the second order derivative of the function.

[tex]v= -26\pi sin[ (5\pi \ rad/s)t+ \frac\pi5][/tex]

[tex]a=\frac{d^2x}{dt^2}[/tex]

 [tex]=\frac{dv}{dt}[/tex]

 [tex]=\frac{d}{dt}( -26\pi sin[ (5\pi \ rad/s)t+ \frac\pi5])[/tex]

 [tex]= -26\pi (5\pi)cos[ (5\pi \ rad/s)t+ \frac\pi5][/tex]

 [tex]= -130\pi^2cos[ (5\pi \ rad/s)t+ \frac\pi5][/tex]

Now we can plug our value t=5.3 into the above equation

[tex]a= -130\pi^2cos[ (5\pi \ rad/s)5.3 \ s+ \frac\pi5][/tex]

  = -753.39 m²/s

(d)

The general equation of SHM is

[tex]x=x_mcos(\omega t+\phi)[/tex]

[tex]x_m[/tex] is amplitude of the displacement, [tex](\omega t+\phi)[/tex] is phase of motion, [tex]\phi[/tex] is phase constant.

So,

[tex](\omega t+\phi)=5\pi t+\frac\pi5[/tex]

Now plugging t=5.3s

[tex](\omega t+\phi)=5\pi \times 5.3+\frac\pi5[/tex]

             =26.7 [tex]\pi[/tex]

The phase motion is 26.7 [tex]\pi[/tex].

The angular frequency [tex]\omega = 5\pi[/tex]

(e)

The relation between angular frequency and frequency is

[tex]\omega =2\pi f[/tex]

[tex]\therefore f=\frac{\omega}{2\pi}[/tex]

     [tex]=\frac{5\pi}{2\pi}[/tex]

    [tex]=\frac52[/tex]

   = 2.5 Hz

Frequency =2.5 Hz.

(f)

The relation between frequency and time period is

[tex]T=\frac1 f[/tex]

   [tex]=\frac1{2.5}[/tex]

  =0.4 s

Time period =0.4 s