Answer
$F = 7.5~N$
Work Step by Step
The impulse applied to the sled is equal to the sled's change in momentum:
$F~t = mv$
$F = \frac{mv}{t}$
$F = \frac{(50.0~kg)(3.0~m/s)}{20.0~s}$
$F = 7.5~N$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.