I want to check myself on some basic things: Assume I am holding a heavy bowling ball straight out in front of me. And assume that when I walk I am able to carry the ball in such a way that it strictly moves in a straight line parallel to the ground (so at a fixed height). My question is: are the following three statements true?

  1. If I walk at the constant velocity $\vec{v}=1\hat{i}$ and there is no drag then no work is being done on the bowling ball
  2. If I walk at the constant velocity $\vec{v}=1\hat{i}$ and there is drag then both I and the air are doing work on the ball: $W_{air on ball}=-W_{meonball}$
  3. If I accelerate while I walk such that my velocity is $\vec{v}=a_{walk}t\hat{i}$ and there is no drag then, for a walk of length $\Delta x$, $W_{meonball}=m_{ball}a_{walk}\Delta x$
  • $\begingroup$ I removed a couple of comments; please keep in mind that comments are to be used for suggesting improvements and requesting clarification on their parent post, not for answering the question. $\endgroup$ – David Z Nov 28 '18 at 5:07

$W = F\Delta d$

where $\Delta d$ is in the direction of the force.

  • Question 1: $\Delta d$ is zero, so no work. Your assertion is true.
  • Question 2: $F$ is the drag, $\Delta d$ is the distance walked. Your assertion is true.
  • Question 3: Since $F = ma$. Your assertion is true.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.