Question

A $3kg$ box slides along a distance of $2.00m$ on a frictionless inclined surface slanted ${30.0}^o$ above the horizontal. How much work is done on the box by gravity, taking $g=9.81m/s^2$?

• A. $0J$
• B. $9.81J$
• C. $14.72J$
• D. $29.43J$
• E. $58.86J$

Answer 1

The correct option is D $29.43J$

Given : $m=3$ kg $L=2.00$ m $g=9.81$ $m/s^2$

From figure, $h=L$ $sin{30}^o=2.00\times 0.5=1.00$ m

Work done by gravity $W=mgh=3\times 9.81\times 1.00=29.43$ J