Answer:
C- Choosing variables and controls
Explanation:
Correct on edge.
Answer:
(a) 37.5 kg
(b) 4
Explanation:
Force, F = 150 N
kinetic friction coefficient = 0.15
(a) acceleration, a = 2.53 m/s^2
According to the newton's second law
Net force = mass x acceleration
F - friction force = m a
150 - 0.15 x m g = m a
150 = m (2.53 + 0.15 x 9.8)
m = 37.5 kg
(b) As the block moves with the constant speed so the applied force becomes the friction force.

No one can answer that kind of question since it was a specific project.
Democritus was a Greek philosopher (470-380 B.C.) who is the father of a modern atomic thought. He proposed that matter could NOT be divided into smaller pieces forever. John Dalton created the very first atomic theory.