the only reason i am wasting one of the two answers your post is allowed to get is because its been 3 hours and no one has answered yet.
Where do you go to school? I think it is very coincidental that you have the exact same question i do, and you had the question exactly when I got the question...about 3 hours ago. Now it IS a curriculum so its not that weird, but by any chance are you in K12? 8th grade?
There are so many examples for that in different areas, like biology experiment carried out in our lab recently.
Here's one link:https://www.creative-biogene.com/support/Knockout-Cell-Lines-in-Antibody-Screening-and-Validation.html
Answer: repel forces and attract forces