# PhysicsForce Flashcards

Terms Definitions
 A push or pull is an example of what? FORCE Force gives energy to an object, sometimes causing it to move how? START MOVING, STOP MOVING, OR CHANGE DIRECTION The total force of an object in one direction is called? UNBALANCED FORCE A force in the opposite direction and equal in size is called? BALANCED FORCE The force that acts in a direction opposite to the motion of the moving object is called? FRICTION What is the direction of force to move an object? IN ONE DIRECTION What is the direction of force in friction? OPPOSITE DIRECTION What is a force that resists motion called? FRICTION What is force that resists the motion? FRICTION What force causes moving objects to slow down and finally stop? FRICTION Does friction produce heat or cold? HEAT What kind of friction causes objects to slide over each other? SLIDING FRICTION What kind of friction causes objects such as wheels or ball bearings? ROLLING FRICTION What kind of friction is causes by a force exerted by a fluid? FLUID FRICTION What are 3 examples of fluid friction? WATER, AIR, OIL What makes falling objects slow down? AIR RESISTANCE How is friction helpful? FRICTION BETWEEN SHOES AND THE GROUND KEEPS US FROM FALLING....FRICTION BETWEEN CAR TIRES AND ROAD A push or a pull is an example of what? FORCE No force is needed to:a. start an object movingb. stop an object movingc. cause a change in the motion of an objectd. keep an object doing what it is already doing KEEP AN OBJECT DOING WHAT IT IS ALREADY DOING When forces are balanced, the motion of the object is:a. decreasedb. increasedc. does not change DOES NOT CHANGE A force that sets an object into motion is:a. inertia b. balanced c. friction d. unbalanced UNBALANCED An example of balanced force is: A BOOK RESTING ON A DESK The sum of balanced forces equals:0, 1, 2, or 3 0 The head of the arrow representing a force indicates what?a. sum b. strengthc. size d. dirction of the force DIRECTION OF THE FORCE Forces that are NOT opposite and equal are called? UNBALANCED Balanced forces cause:a. a moving particle to slow downb. a moving particle to speed upc. no change in motiond. a change in direction NO CHANGE IN MOTION Which of these is not used to reduce friction?a. oilb. wheelsc. rough surfacesd. ball bearings ROUGH SURFACES Which of these if not a fluid?a. waterb. air c. sugard. oil SUGAR If there is an unbalanced force in an arm-wrestling match, do both arms move in the direction of the smaller or larger force? SMALLER FORCE The amount of sliding friction depends ona. the weight of moving object and type of surfaceb. the density and volume of an objectc. the acceleration and mass of object THE WEIGHT OF MOVING OBJECT AND TYPE OF SURFACE OBJECT SLIDES ACROSS The direction of the frictional force on a moving object is OPPOSITE THE MOTION OF THE MOVING OBJECT Wheels and ball bearings change sliding friction to what? ROLLING FRICTION The function of lubricants is to change what? SLIDING FRICTION TO FLUID FRICTION Do treads on tires increase or reduce friction? INCREASE An example of friction other than sliding or rolling is?a. pushing a desk across floorb. walking across the floorc. riding a skateboardd. floating downward after diving off a cliff FLOATING DOWNWARD AFTER DIVING OFF A CLIFF An example of rolling friction is:a. a stack of cartons being pushed across the floorb. the use of ball bearingsc. sand placed on icy ground THE USE OF BALL BEARINGS When a car moves at constant velocity, what happens?a. wheels are balancedb. frictional force is c. greater that the engine's forced. engine's force is greater than the frictional force THE ENGINE'S FORCE IS GREATER THAN THE FICTIONAL FORCE The combination of w forces exerted in opposite directions is? THE DIFFERENCE BETWEEN THE TWO FORCES The Law of Motion that describes action-reaction is called? THIRD LAW When 2 forces acting in the same direction are applied to mass,the combined force isa. sum of the 2 forcesb. product of 2 forcesc. difference between 2 forces SUM OF THE 2 FORCES An example of fluid friction is:a. rolling frictionb. air resistancec. sliding friction AIR RESISTANCE For every action the reaction is:a. equal, in same directionb. equal and oppositec. unequal,in same directiond. unequal and opposite EQUAL AND OPPOSITE A standoff in an arm-wrestling match is due to what? BALANCED FORCES One newton equals one what? KILOGRAM A greyhound accelerated up to 3m/sec/sec.What is the net force needed to give a 35kg dog this acceleration? F = M x AF = 35 x 3 msec2F = 105N A 65 kg high diver jumps with a downward acceleration of 9 m/sec/sec.What is his net force? F = M x AF = 65 x 9 msec2F = 585 m/sec2 What do you call the sum of the forces acting on an object? NET FORCE Force is measured in what? NEWTONS What is the equation for net force? MASS x ACCELERATION Near the surface of the Earth, the acceleration due to gravity is 9.8 m/sec/sec. After falling 5 seconds, an object would have a velocity of what? 49 m/sec2 The weight of an object varies with:a. pull of gravityb. volume of the objectc. dimensions of the object VOLUME OF THE OBJECT A book resting on a desk has unbalanced forces action on it or has weight due to gravitational force? WEIGHT DUE TO GRAVITATIONAL FORCE Gravitational force between 2 objects depends on the:a. distance between the objects onlyb.masses of the objects and the distance between themc. inertia and masses of the objects MASSES OF THE OBJECTS AND THE DISTANCE BETWEEN THEM What is the tendancy of an object to resist any change in motion? INERTIA A mass of 5 kg has a weight of what? 9.8 x 5 = If you were on the moon, there would be a change in your: a. volumeb. weightc. mass WEIGHT Do all falling objects accelerate at the same rate? YES If an object is accelerating, what is the force called? GRAVITY The acceleration due to gravity at the surface of the Earth is how fast? 9.8 m/secEVERY SECOND AN OBJECT IS FALLING, ITS VELOCITY IS INCREASINGT An object dropped from a roofhas a velocity of how much at 2 seconds? ONE SECOND = 9.8 m/secTWO SECONDS = 19.6 m/sec Do a leaf and and a rock fall at 9.8 m/sec/sec? NO, BECAUSE THE SHAPE OF THE LEAF CAUSES GREATER AIR RESISTANCE AND SLOWS IT DOWN. "All objects in the universe attract each other by the force of gravity" is called what? NEWTONS LAW OF UNIVERSAL GRAVITY
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