Question: what is the force that pulls on objects and causes acceleration

title: Centrifugal force
text: The apparent acceleration in the rotating frame is ( d r / dt ) . An observer unaware of the rotation would expect this to be zero in the absence of outside forces . However , Newton 's laws of motion apply only in the inertial frame and describe dynamics in terms of the absolute acceleration d r / dt . Therefore , the observer perceives the extra terms as contributions due to fictitious forces . These terms in the apparent acceleration are independent of mass ; so it appears that each of these fictitious forces , like gravity , pulls on an object in proportion to its mass . When these forces are added , the equation of motion has the form : 

Answer: answer: Newton's laws of motion apply only in the inertial frame and describe dynamics in terms of the absolute acceleration.  Each of these fictitious forces, like gravity, pulls on an object in proportion to its mass, and it is called centrifugal force.