5CHAPTER OUTLINE5.1 The Concept of Force5.2Newton’s First Law andInertial Frames5.3Mass5.4Newton’s Second Law5.5The Gravitational Forceand Weight5.6Newton’s Third Law5.7Some Applications ofNewton’s Laws5.8Forces of FrictionThe Laws of MotionANSWERS TO QUESTIONSQ5.1(a)The force due to gravity of the earth pulling down onthe ball—the reaction force is the force due to gravityof the ball pulling up on the earth. The force of thehand pushing up on the ball—reaction force is ballpushing down on the hand.(b)The only force acting on the ball in free-fall is thegravity due to the earth -the reaction force is thegravity due to the ball pulling on the earth.Q5.2The resultant force is zero, as the acceleration is zero.Q5.3Mistake one: The car might be momentarily at rest, in theprocess of (suddenly) reversing forward into backward motion.In this case, the forces on it add to a (large) backward resultant.
This is the end of the preview.
access the rest of the document.