We read your photo as:

Calculate the work done by the force F = 3x2 i + (2x-y) j + z k along the curve parameterized by x = 2t2, y = t, z = 4t2 − t, from t=0 to t=1.

Physics

ScanSolve AI Answer

Answer

403\frac{40}{3}

Graph of y = t

Use the left and right arrow keys to trace the curve, up and down to jump between key points, and plus and minus to zoom.

Key points of y = t
Pointty
x-intercept00

Step-by-step solution

6 steps
  1. Write the formula for work done.

    The work done WW by a force F\mathbf{F} along a curve CC is given by the line integral:

    W=∫CF⋅drW = \int_C \mathbf{F} \cdot d\mathbf{r}

    The force is given as F=3x2i+(2x−y)j+zk\mathbf{F} = 3x^2 \mathbf{i} + (2x-y) \mathbf{j} + z \mathbf{k}.
    The curve is parameterized by x=2t2x = 2t^2, y=ty = t, z=4t2−tz = 4t^2 - t, from t=0t=0 to t=1t=1.

  2. Express F\mathbf{F} in terms of tt.

    Substitute x=2t2x = 2t^2, y=ty = t, and z=4t2−tz = 4t^2 - t into the expression for F\mathbf{F}:

    Fx=3x2=3(2t2)2=3(4t4)=12t4F_x = 3x^2 = 3(2t^2)^2 = 3(4t^4) = 12t^4 Fy=2x−y=2(2t2)−t=4t2−tF_y = 2x-y = 2(2t^2) - t = 4t^2 - t Fz=z=4t2−tF_z = z = 4t^2 - t

    So, F(t)=12t4i+(4t2−t)j+(4t2−t)k\mathbf{F}(t) = 12t^4 \mathbf{i} + (4t^2 - t) \mathbf{j} + (4t^2 - t) \mathbf{k}.

  3. Find drd\mathbf{r} in terms of tt.

    The position vector is r(t)=x(t)i+y(t)j+z(t)k\mathbf{r}(t) = x(t) \mathbf{i} + y(t) \mathbf{j} + z(t) \mathbf{k}.

    r(t)=2t2i+tj+(4t2−t)k\mathbf{r}(t) = 2t^2 \mathbf{i} + t \mathbf{j} + (4t^2 - t) \mathbf{k}

    Now, find the differential dr=drdtdtd\mathbf{r} = \frac{d\mathbf{r}}{dt} dt:

    dxdt=ddt(2t2)=4t\frac{dx}{dt} = \frac{d}{dt}(2t^2) = 4t dydt=ddt(t)=1\frac{dy}{dt} = \frac{d}{dt}(t) = 1 dzdt=ddt(4t2−t)=8t−1\frac{dz}{dt} = \frac{d}{dt}(4t^2 - t) = 8t - 1

    So, dr=(4ti+1j+(8t−1)k)dtd\mathbf{r} = (4t \mathbf{i} + 1 \mathbf{j} + (8t - 1) \mathbf{k}) dt.

  4. Calculate the dot product F⋅dr\mathbf{F} \cdot d\mathbf{r}.

    F⋅dr=(Fxdxdt+Fydydt+Fzdzdt)dt\mathbf{F} \cdot d\mathbf{r} = (F_x \frac{dx}{dt} + F_y \frac{dy}{dt} + F_z \frac{dz}{dt}) dt F⋅dr=((12t4)(4t)+(4t2−t)(1)+(4t2−t)(8t−1))dt\mathbf{F} \cdot d\mathbf{r} = \left( (12t^4)(4t) + (4t^2 - t)(1) + (4t^2 - t)(8t - 1) \right) dt F⋅dr=(48t5+4t2−t+(32t3−4t2−8t2+t))dt\mathbf{F} \cdot d\mathbf{r} = \left( 48t^5 + 4t^2 - t + (32t^3 - 4t^2 - 8t^2 + t) \right) dt F⋅dr=(48t5+4t2−t+32t3−12t2+t)dt\mathbf{F} \cdot d\mathbf{r} = \left( 48t^5 + 4t^2 - t + 32t^3 - 12t^2 + t \right) dt

    Combine like terms:

    F⋅dr=(48t5+32t3+(4t2−12t2)+(−t+t))dt\mathbf{F} \cdot d\mathbf{r} = \left( 48t^5 + 32t^3 + (4t^2 - 12t^2) + (-t + t) \right) dt F⋅dr=(48t5+32t3−8t2)dt\mathbf{F} \cdot d\mathbf{r} = (48t^5 + 32t^3 - 8t^2) dt
  5. Integrate from t=0t=0 to t=1t=1.

    W=∫01(48t5+32t3−8t2)dtW = \int_0^1 (48t^5 + 32t^3 - 8t^2) dt W=[48t66+32t44−8t33]01W = \left[ \frac{48t^6}{6} + \frac{32t^4}{4} - \frac{8t^3}{3} \right]_0^1 W=[8t6+8t4−83t3]01W = \left[ 8t^6 + 8t^4 - \frac{8}{3}t^3 \right]_0^1
  6. Evaluate the definite integral.

    W=(8(1)6+8(1)4−83(1)3)−(8(0)6+8(0)4−83(0)3)W = \left( 8(1)^6 + 8(1)^4 - \frac{8}{3}(1)^3 \right) - \left( 8(0)^6 + 8(0)^4 - \frac{8}{3}(0)^3 \right) W=(8+8−83)−(0)W = \left( 8 + 8 - \frac{8}{3} \right) - (0) W=16−83W = 16 - \frac{8}{3}

    To subtract, find a common denominator:

    W=16×33−83W = \frac{16 \times 3}{3} - \frac{8}{3} W=483−83W = \frac{48}{3} - \frac{8}{3} W=403W = \frac{40}{3}

    The work done is 403\frac{40}{3}.

Was this helpful?

Try one yourself

A new problem that tests the same skill.

Still stuck on this one?

Ask a follow-up, and the answer starts from this question.

Got a different question?Ask your own question
Handwritten step-by-step solution preview

Handwritten Step-by-Step Solution

Get this as a handwritten image on WhatsApp — like a tutor wrote it for you.

Try on WhatsApp