Question

$300\, J$ of work is done in sliding a $2 kg$ block up an inclined plane of height $10 \,m$. Taking $g=10\, m / s ^{2}$, work done against friction is :

• A. 200 J
• B. 100 J
• C. zero
• D. 1000 J

Answer 1

Answer: (B)

100 J

Answer 2

Net work done in sliding a body up to a height h on inclined plane $=$ Work done against gravitational force $+$ Work done againstfrictional force $\Rightarrow W=W_{g}+W_{f} \,\,\,. ..$ (i) but $W=300\, J$ $W_{g}=m g h=2 \times 10 \times 10=200\, J$ Putting in E (i), we get $300=200+W_{f}$ $\Rightarrow W_{f}=300-200$ $=100\, J$