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Work, Energy, and Power — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysicsWork, Energy, and Power5 Marks
Question
A block of weight $100N$ is slowly slid up on a smooth incline of inclination $37^\circ$ by a person. Calculate the work done by the person in moving the block through a distance of $2.0m$, if the driving force is:
  1. Parallel to the incline.
  2. In the horizontal direction.
✓

Answer

$\text{W}=100\text{N},\theta=37^\circ,\text{S}=2\text{m}$`
  1. $\text{F}=\text{mg}\sin37^\circ=100\times0.60=60\text{N}$
So, work done, when the force is parallel to incline.
$\text{W}=\text{FS}\cos\theta=60\times2\times\cos\theta=120\text{J}$
  1. In $\triangle\text{ABC }\text{AB}=2\text{m}$
$CB = 37^\circ$
So, $h = C = 1m$
$\therefore$ Work done when the force in horizontal direction.
$W = mgh = 100 \times 1.2 = 120J$

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