Question

The work done in pulling up a block of wood weighing $ 2\,\,kN $ for a length of $ 10\,\,m $ on a smooth plane inclined at an angle of $ {{15}^{o}} $ with the horizontal is:

• A. $ 9.82\,\,kJ $
• B. $ 89\,\,kJ $
• C. $ 4.35\,\,kJ $
• D. $ 5.17\,\,kJ $

Answer 1

Answer: (D)

Here : weight of block $w=2 \,kN$, Distance $d=10\, m$
Angle of inclination on the plane $\alpha=15^{\circ}$
The block will be pulled up on a smooth plane
Hence, force of resistance due to inclination
$F =w \sin \alpha=2 \times 10^{3} \sin 15^{\circ} $
$=2 \times 10^{3} \times 0.2588 $
$=0.5176 \,kN$
Now work done,
$W =F d=0.5176 \times 10^{3} \times 10$
$=5: 17\, kN$