Thank you everyone for your responses. I would only like to know how Newton knew his laws are true. What were the experiments he performed?

I just see the example shown by a drawing. What variables are being measured there? How are they measured?

Thank you for your answer. What are the experiments that Newton used to show their laws are true?

Sorry if I seem ignorant, but how can we know they are true then?

Thank you all for your answers. They have somehow help me to think about the situation. Does someone just know what were the experiments Newton performed to prove his laws?

Lets say you use a chronometer. The chronometer uses f=ma to perform calculations.

But what if the equipment need the laws to be true?

Thank you guys for your answers. Tim, by "prove" I mean how can you show they are true. I hope this can help.