A single, nonconstant force acts in the + x ‑direction on an object of mass M that is constrained to move along the x ‑axis. As a result, the object's position as a function of time is x ( t ) = P + Q t + R t 3 How much work W is done by this force from t = 0 s to final time T ? Express the answer in terms of P , Q , R , M , and T .

Respuesta :

Answer:

Velocity  [tex]V = \frac{dx}{dt} = \frac{d}{dt} (P + Qt + Rt^{3})[/tex]

               [tex]V = 0 + Q(1) + 3Rt^{2}[/tex]

               V  = Q + 3Rt²

at t = 0, [tex]v_{i}[/tex] = Q + 3r(0) ==> Q

at t = T, [tex]v_{f}[/tex] = Q + 3rT²

Work done (W) = ΔKE = [tex]\frac{1}{2} m(v_f^{2} - v_i^{2})[/tex]

W = [tex]\frac{1}{2} m[(Q + 3RT^{2})^{2} - Q^{2}][/tex]

W =  [tex]\frac{1}{2} m[/tex] [Q² + 9R²T⁴ + 2Q(3RT²) - Q²]

W =  [tex]\frac{1}{2} m[/tex] (9R²T⁴ + 6QRT²)

Explanation:

Differentiate the position.

Find the equation for speed.

Find the initial and final speed.

Use work energy theorem to find the work done by finding the change in kinetic energy.

The work done by the force from t = 0 to T can be expressed by the equation [tex]\ \dfrac 12 m (9R^T^2 + 6QRT^2)[/tex].

What is work?

Work can be defined as the product of the applied force and displacement of an object.

Differentiate the position,

[tex]V = \dfrac {dx }{dt}\\V = \dfrac d {dt }(P+Qt+Rt^3)\\V = 0 + Q\times 1 + 3 Rt^2[/tex]

The initial speed at [tex]T= 0[/tex], the initial velocity [tex]v_i = Q[/tex]

The final speed at  t = T. the final velocity  [tex]v_f = Q +3 rT^2[/tex]

From work- energy formula,

[tex]W = \dfrac 12 m (v_f ^2 - v_i^2 )[/tex]

Put the values in the formula,

[tex]W = \dfrac 12 m (Q +3RT^2 )^2- Q^2\\\\W = \dfrac 12 m [Q² + 9R^2T^4+ 2Q(3RT^2) - Q^2]\\\\\ W = \dfrac 12 m (9R^T^2 + 6QRT^2)[/tex]

Therefore, the work done by the force from t = 0 to T can be expressed by the equation [tex]\ \dfrac 12 m (9R^T^2 + 6QRT^2)[/tex].

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