It's not so much a "contradiction" as an approximation. Newton's law of gravitation is an inverse square law whose range is large. It keeps people on the ground, and it keeps satellites in orbit and that's some thousands of km. The force on someone on the ground - their weight - is probably a lot larger than the centripetal force keeping a satellite in orbit (though I've not actually done a calculation to totally verify this). The distance a falling body - a coin, say - travels is very small, and over such a small distance gravity is assumed/approximated to be constant.
Hi there!
The answer would be B. the slope of the plane.
Changing the slope of the plane would show how fast the ball went when Galileo changed the steepness of the slope. If he didn’t change the slopes steepness he would have the same results each time.
Hope this helps !
1 Joule IS 1 newton-meter.
True because the atmosphere is in the way
A. 20m/s because the unit for velocity is m/s