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Name:Per:6.A rightward force is applied to abook in order to move it across adesk at constant velocity.Consider frictional forces.Neglect air resistance. Diagramthe forces acting on the book.A book is at rest on a table top.Diagram the forces acting on thebook.7.A girl is suspended motionlessfrom the ceiling by a trapeze barattached to two ropes. Diagramthe forces acting on thecombination of girl and bar.A college student rests abackpack upon his shoulder. Thepack is suspended motionless byone strap from one shoulder.Diagram the vertical forcesacting on the backpack.8.A skydiver is descending with aconstant velocity. Consider airresistance. Diagram the forcesacting upon the skydiver.An egg is free-falling from a nestin a tree. Neglect air resistance.Diagram the force acting on theegg as it is falling.9.A force is applied to the right todrag a sled across loosely-packedsnow with a rightwardacceleration. Diagram the forcesacting upon the sled.Free Body Diagram PracticeRead each scenario and draw a diagram of the forces acting upon the object(s).1.2.3.4.5.A flying squirrel is gliding(no wing flaps) from a tree tothe ground at constant velocity.Consider air resistance. Diagramthe forces acting on the squirrel.A rightward force is applied to abook in order to move it across adesk with a rightwardacceleration. Consider frictionalforces. Neglect air resistance.Diagram the forces acting on thebook.10. A football is moving upwardstowards its peak after havingbeen booted by the punter.Diagram the forces acting uponthe football as it rises upwardtowards its peak.11. A car is coasting to the right andslowing down. Diagram theforces acting upon the car.
Free Body Diagram Practice KEYType of ForceDescription of Force(and Symbol)Applied ForceFappGravity Force(also known asWeight)FgravAn applied force is a force which is applied to an object by aperson or another object. If a person is pushing a desk acrossthe room, then there is an applied force acting upon theobject. The applied force is the force exerted on the desk bythe person.The force of gravity is the force with which the earth, moon,or other massively large object attracts another objecttowards itself. By definition, this is the weight of the object. Allobjects upon earth experience a force of gravity which isdirected "downward" towards the center of the earth. Theforce of gravity on earth is always equal to the weight of theobject as found by the equation:Fgrav m * g2Normal ForceFnormFriction ForceFfrictwhere g 9.8 m/s (on Earth)and m mass (in kg)The normal force is the support force exerted upon an objectwhich is in contact with another stable object. For example, ifa book is resting upon a surface, then the surface is exertingan upward force upon the book in order to support the weightof the book. On occasions, a normal force is exertedhorizontally between two objects which are in contact witheach other. For instance, if a person leans against a wall, thewall pushes horizontally on the person.The friction force is the force exerted by a surface as an objectmoves across it or makes an effort to move across it. Thereare at least two types of friction force - sliding and staticfriction. Thought it is not always the cast, the friction forceoften opposes the motion of an object. For example, if a bookslides across the surface of a desk, then the desk exerts afriction force in the opposite direction of its motion. Frictionresults from the two surfaces being pressed together closely,causing intermolecular attractive forces between molecules ofdifferent surfaces. As such, friction depends upon the natureof the two surfaces and upon the degree to which they arepressed together. The maximum amount of friction forcewhich a surface can exert upon an object can be calculatedusing the formula below:The friction force is discussed in more detail later on this page.Air Resistance Force The air resistance is a special type of frictional force which actsupon objects as they travel through the air. The force of airFairresistance is often observed to oppose the motion of anTension ForceFtensSpring ForceFspringobject. This force will frequently be neglected due to itsnegligible magnitude (and due to the fact that it ismathematically difficult to predict its value). It is mostnoticeable for objects which travel at high speeds (e.g., askydiver or a downhill skier) or for objects with large surfaceareas. Air resistance will be discussed in more detail in Lesson3.The tension force is the force which is transmitted through astring, rope, cable or wire when it is pulled tight by forcesacting from opposite ends. The tension force is directed alongthe length of the wire and pulls equally on the objects on theopposite ends of the wire.The spring force is the force exerted by a compressed orstretched spring upon any object which is attached to it. Anobject which compresses or stretches a spring is always actedupon by a force which restores the object to its rest orequilibrium position. For most springs (specifically, for thosewhich are said to obey "Hooke's Law"), the magnitude of theforce is directly proportional to the amount of stretch orcompression of the spring.
1. A book is at rest on a table top. A free-body diagram for this situation looks likethis:2. A girl is suspended motionless from the ceiling by two ropes. A free-body diagramfor this situation looks like this:6. A rightward force is applied to a book in order to move it across a desk atconstant velocity. Consider frictional forces. Neglect air resistance. A free-bodydiagram for this situation looks like this:7. A college student rests a backpack upon his shoulder. The pack is suspendedmotionless by one strap from one shoulder. A free-body diagram for this situationlooks like this:3. An egg is free-falling from a nest in a tree. Neglect air resistance. A free-bodydiagram for this situation looks like this:8. A skydiver is descending with a constant velocity. Consider air resistance. A freebody diagram for this situation looks like this:4. A flying squirrel is gliding (no wing flaps) from a tree to the ground at constantvelocity. Consider air resistance. A free-body diagram for this situation looks likethis:9. A force is applied to the right to drag a sled across loosely-packed snow with arightward acceleration. A free-body diagram for this situation looks like this:10. A football is moving upwards towards its peak after having been booted by thepunter. A free-body diagram for this situation looks like this:5. A rightward force is applied to a book in order to move it across a desk with arightward acceleration. Consider frictional forces. Neglect air resistance. A freebody diagram for this situation looks like this:11. A car is coasting to the right and slowing down. A free-body diagramfor this situation looks like this:
Free Body Diagram Practice Read each scenario and draw a diagram of the forces acting upon the object(s). 1. A book is at rest on a table top. Diagram the forces acting on the book. 2. A girl is suspended motionless from the ceiling by a trapeze bar attached to two ropes. Diagram the forces
