Question

Suppose that there is a 10 kg box, which is initially at rest, on the floor. Now you start dragging it with an applied force of 100 N directed to the right along the horizontal. There is frictional force of 25 N on the box. The box moves 2m.

FIND:
A.) Work done by applied force
B.) Work done by frictional force
C.) Work done by the weight of the box

Answer 1

Answer:

A) work done by applied force

Answer 2

$\blue{\bold{\underline{\underline{Answer:}}}}$

$\green{\tt{\therefore{Work\:Done\:by\:force\:applied=200\:J}}}$

$\green{\tt{\therefore{Work\:Done\:by\:frictional\:force=-50\:J}}}$

$\green{\tt{\therefore{Work\:Done\:by\:weight\:of\:box=0\:J}}}$

$\orange{\bold{\underline{\underline{Step-by-step\:explanation:}}}}$

$\green{\underline{\bold{Given :}}}$

$\tt: \implies Mass \: of \: box (m)= 10 \: kg$

$\tt: \implies Applied \: force(F) = 100 \:N$

$\tt: \implies Friction \: force(fr) = 25 \: N$

$\tt: \implies Displacement(s) = 2 \: m$

$\red{\underline{\bold{To \: Find :}}}$

$\tt: \implies Work \: Done \: by \: applied \: force(w_{F} ) = ?$

$\tt: \implies Work \: Done \: by \: frictional \: force(w_{fr} ) =?$

$\tt: \implies Work \: Done \: by \: weight \:of \: box(w_{m} ) = ?$

• According to given question :

$\bold{As \: we \: know \: that}$

$\tt: \implies Work \: done = Force \: applied \times Displacement$

$\tt: \implies w_{F} = 100 \times 2$

$\green{\tt: \implies w_{F} = 200 \: joule}$

$\bold{Again: }$

$\tt: \implies w_{fr} =fs\: cos \: \theta$

$\tt: \implies w_{fr} = 25 \times 2 \times cos \: 180 \degree$

$\green{\tt: \implies w_{fr} = - 50 \: joule}$

$\tt \circ \: Weight \: of \: box = mg = 100 \: N$

$\tt \circ \: Angle \: between \: force \: and \: displacement = 90 \degree$

$\bold{Similarly : }$

$\tt: \implies w_{m} = fs \: cos \: \theta$

$\tt: \implies w_{m} = 100 \times 2 \times cos \: 90 \degree$

$\tt: \implies w_{m} = 100 \times 2 \times 0$

$\green{ \tt: \implies w_{m} = 0 \: joule}$