Question

if $250J$ of work is done in sliding a $5kg$ block up an inclined plane of height $4m$ work done against fiction $g=10m{s}^{-2})$

• A. $50J$
• B. $100J$
• C. $200J$
• D. Zero

Answer 1

The correct option is A $50J$

For calculating work done when friction is involved,

Total work done(W)is equal to Work done against friction$\left(W_1\right)+$ Work done against gravity$\left(W_2\right)$

Given:

Total work is done $\left(W\right)=250J$

$Mass\left(m\right)=5kg$

Therefore, $Weight\left(w\right)=5\times 10=50N$

$Height\left(h\right)=4m$

$W=W_1+W_2$

$\Rightarrow W=W_1+(w\times h)$

$\Rightarrow 250=W_1+50\times 4)$

$\Rightarrow W_1=250-200$

$\Rightarrow W_1=50$

Hence work done against friction is $50J$