Answer:
If Black Holes Are "Black," How Do Scientists Know They Are There? A black hole can not be seen because strong gravity pulls all of the light into the middle of the black hole. But scientists can see how the strong gravity affects the stars and gas around the black hole.
Explanation:
some examples; 1. Pushing a wheel barrow.
2. Opening or closing a door.
3. Squeezing wet clothes.
4. Gravitational force.
5. Brakes applied to stop a moving vehicle.
6. A football kicked harder that decreases due to the frictional force.
7. Rubbing a glass rod with a silk.
8. Pressure applied on a pin of a notice board.
9. Running
10. Pushing