# ScienceChapter2

 Forces that are equal in size but opposite in direction are ____. balanced forces If gravity did not affect the path of a horizontally thrown ball, the ball would ____. travel horizontally Newton's first law of motion states that an object remains at rest unless a ____ force acts on it. Net The force you have to overcome to start an object moving is ____. Static Friction Whenever a body is in motion, there is always ____ to oppose the motion. Friction The relationship among force, mass, and acceleration is stated in ____. Newton's second law of motion According to Newton's second law of motion, ____. a = Fnet /m A 3,000-N force gives an object an acceleration of 15 m/s2. The mass of the object is ____. 200 KG. A 300-N force acts on a 25-kg object. The acceleration of the object is ____. 12 m/s 2 The statement "for every action, there is an equal but opposite reaction" is a statement of ____. Newtons Third Law With action-reaction forces, ____. The forces are created at the same time. Inertia is a measure of the ____ of an object. mass The unit of force is ____. The Newton When two birds are pulling on a worm and the worm moves toward the first bird, you know that the forces are ____. Unbalanced An unbalanced force acting on an object causes it to ____. Accelerate A planet is discovered that is the same size as Earth and has the same gravitational acceleration, but has twice the mass. If you weigh 700 N on Earth, on the new planet you would weigh ____. 1400 N The force that opposes motion is ____. Friction. Every force has a(n) _____ force. opposite You throw a ball into the air. As the ball leaves your hand, the force(s) acting on it is/are ____. Gravity and your hand A student has a set of masses to use in an experiment about force. Which of the following masses would require the least amount of force to be lifted from the lab table? 1-g mass Which statement best describes how the mass of an object affects the amount of force needed to move the object? Larger masses require more force to move The force that acts ____ to the direction of motion is called centripetal force. Perpendicular. A centripetal force holds the planets of the solar system in orbit about the Sun. This force is the result of ____. Gravity. Figure 1 shows the path of a ball that was thrown up into the air. At which point in the path of the ball are all the forces on the ball balanced? point 3. Figure 1 shows the path of a ball that was thrown up into the air. Which of the following is not acting on the ball in the diagram? Static Friction Refer to Figure 2. Which pair of force vectors represents an object that is accelerating to the right? Pair c. Refer to Figure 2. Which pair of force vectors represents balanced forces? Pair A. Refer to Figure 2. Which pair of force vectors represents an object that is falling? Pair B. Refer to Figure 2. Which pair of force vectors represents acceleration to the left? Pair D. A student sees a motionless ball resting on a table. Which of the following best describes the forces acting on the ball? Gravity is creating a downward force that is equal to the force of the table pushing up. Figure 3 shows forces acting on a car. Which statement best predicts the motion of the car? The car will move forward. Figure 4 shows a ball and the forces acting on it. Which pair of terms best predicts how the ball should be moving? to the left and down Which diagram in Figure 5 shows static friction resisting the motion of a book? diagram c In which diagram in Figure 5 is the book most likely to be moving horizontally? Diagram B Figure 6 shows three book sitting on a table. How many opposing pairs of force vectors are needed to describe the forces acting on book B? 3 Authormerissaalexis ID43906 Card SetScienceChapter2 Description8th grade science chapter 2 study guide Updated2010-10-21T03:39:11Z Show Answers