Question

A constant horizontal $4.0N$ force acts on a $300g$ cart on a horizontal track as the cart moves through a distance of $43.0cm$. The cart decelerates as a result.
What was the work performed on the cart by the force?

• A. $-1.72J$
• B. $-1.27J$
• C. $1.27J$
• D. $1.72J$
• E. None of the above

Answer 1

The correct option is A $-1.72J$

Given : $F=4.0$ N $S=43.0$ cm $=0.43$ m

As the cart decelerates, this means the force acts opposite to the direction of velocity (or displacement).

Work done by a force $W=FS$ $cos\theta$ where $\theta$ is the angle between $F$ and $S$

$\therefore$ $W=4.0\times 0.43\times cos{180}^o=-1.72$ J