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

The Correct Option is 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, $W =F d=0.5176 \times 10^{3} \times 10$ $=5: 17\, kN$