Physics

Problem

A gardener pushes a lawn-mower on a level lawn by applying a constant force of

200\,\text{N}

at an angle

\theta

to the horizontal while the mower moves in a straight line. a. (i) Define work and state its SI unit. b. (ii) Explain qualitatively how the sign and magnitude of the work done by the gardener change as

\theta

varies from

0^{\circ}

180^{\circ}

. State the ranges of

\theta

for which the work is (a) positive, (b) zero and (c) negative. c. (iii) If the mower is pushed through

10\,\text{m}

with

\theta = 60^{\circ}

, calculate the numerical value of the work done. Would this work increase or decrease if the angle were reduced to

30^{\circ}

while all other quantities remain the same? Give a brief reason.

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