contestada

A 12.0N force with a fixed orientation does work on a
particleas the particle moves through displacement d=(2.00i -4.00j
+3.00k)m. What is the angle between the force and thedisplacement
if the change in the particle's kinetic energy is a)+30.0J and b)
-30.0J ?

Respuesta :

Answer:

(a) [tex]\theta=62.31^{\circ}[/tex]

(b) [tex]\theta=117.68^{\circ}[/tex]

Explanation:

It is given that,

Force acting on the particle, F = 12 N

Displacement of the particle, [tex]d=(2.00i -4.00j+3.00k)\ m[/tex]

Magnitude of displacement, [tex]d=\sqrt{2^2+4^2+3^2}= 5.38\ m[/tex]

(a) If the change in the kinetic energy of the particle is +30 J. The work done by the particle is given by :

[tex]W=Fd\ cos\theta[/tex]

[tex]\theta[/tex] is the angle between force and the displacement

According to work energy theorem, the charge in kinetic energy of the particle is equal to the work done.

So,

[tex]cos\theta=\dfrac{W}{Fd}[/tex]

[tex]cos\theta=\dfrac{+30\ J}{12\times 5.38}[/tex]

[tex]\theta=62.31^{\circ}[/tex]

(b) If the change in the kinetic energy of the particle is (-30) J. The work done by the particle is given by :

[tex]cos\theta=\dfrac{W}{Fd}[/tex]

[tex]cos\theta=\dfrac{-30\ J}{12\times 5.38}[/tex]

[tex]\theta=117.68^{\circ}[/tex]

Hence, this is the required solution.