What challenges did galileo, sir isaac newton, and albert einstein have to face?

When using the scientist method, which step comes last?

Ball bearings are made by letting spherical drops of molten metal fall inside a talll tower-called a shot tower- and solidify as they fall. a-if a bearing needs 4.0 s to solidify enough for impact, how high must the tower be? b- what is the bearing's impact velocity?

Adistance-time graph indicates than an object moves 100 m in 4 s and then remains at rest for 6 s. what is the average speed of the object?