Question

During some part of the motion, the work done on the cart is negative. What feature of the motion indicates this? A. The speed is increasing.B. The speed is decreasing.C. The acceleration is positive.D. The acceleration is negative. Is work related to speed or is work related to acceleration? Explain how work is related to speed or acceleration.

Answer 1

In order to find when the work is negative, let's analyze the two formulas below: for the work done by a force and for the net force in an object:

$\begin{gathered} W=F\cdot d\\ \\ F=m\cdot a \end{gathered}$

Looking at the formulas, we can see that when the acceleration is negative, the force is negative, and then the work will also be negative.

Therefore the correct option is D.

The work is related to the acceleration, as we can see from the two formulas above.