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Physics Measuring Motion
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Point of reference An object that ____________compared to an object that is _____________. Examples: ___________, mountains on Earth, buildings, trees, etc
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Motion An objects change in __________ relative to a ___________ point. Time = x-axis Distance = y-axis.
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This line is not horizontal (at rest)
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A B C
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Speed Vs. Velocity Speed = Rate at which _______ changes over _______.S = D/t Velocity = speed with _____________ V = D/t with a direction (right, left, north, south, negative, positive) When writing units you can write: 1. meters per second 2. m/s 3. mps
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A bus moves a distance of 150 m East in 10 seconds. 1. What is the bus’s average speed? 2. What is the bus’s average velocity? 3. What are the passengers on the bus’s average velocity (assume no passengers are moving)? 4. If a passenger stands up and starts moving 1 m/s East, what is the passengers total velocity? 5. If another passenger stands up and starts moving 1 m/s West what is the passengers total velocity?
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Acceleration The rate at which ________ changes over ____ Avg Acceleration = Final Velocity – Starting Velocity time it takes to change velocity What is the bicyclist’s acceleration? (Include direction)
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Avg Acceleration = Final Velocity – Starting Velocity time it takes to change velocity Acceleration = ( - ) = ( – ) All units for acceleration are in distance/time 2 with a direction
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Velocity Versus Time Graph 1.What is happening from 0 seconds to 8 seconds? 2.What is happening from 8 to 10 seconds? 3.What happens at exactly 8 seconds? 4.What happens to this person’s position from 0 –10 seconds?
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Circular Motion Objects moving in ________ always change _________, ________, and ____________ Black arrow indicates direction of motion and velocity. Blue arrow indicates acceleration.
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Forces
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FORCES: Push or pull on an object balanced forces = ________________ (all forces add up to be zero) unbalanced forces = ________________ (all forces add up to NOT be zero)
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Friction: force that __________ motion. Kinetic Friction: Occurs when the object is _________. (Ball ________ down a hill) Static Friction: Occurs when the object is __________ or ____ moving. (Book ____ sliding off ramp of desk)
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Free Body Diagram Box Sitting on the table, at rest Force of Gravity (F g ) Normal Force (F N ): Force acting _____________ to the surface the object is on. In this situation the force of gravity is _________ out by the ________ force so the net force is 0. Therefore the box is not moving up or down. 15 N
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Free Body Diagram Box being pushed to the right with 20 Newton Force. Force of Gravity (F g ) Normal Force (F N ) Force of Friction (F f ): The force the __________motion. Pushing Force (F P ) = 20 N In this situation the normal force and force of gravity are __________ so the box does not move up or down. The pushing force is 20 N to the right and from the arrow the force of friction appears ________ so the box will move to the right. Net Force = 15 N 10 N 15 N
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Free Body Diagram Box on ramp Force of Gravity (F g ) Normal Force (F N ) Force of Friction (F f ): Friction is always ________ to the surface the object is on. Does the box move down the ramp? The box slides down the ramp if the force of gravity in the x direction is greater than the force of ______. The box does not move if the force of gravity in the x direction is _____ than the force of friction.
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There are ____ types of friction that occur when a force opposes the motion of a moving object. __________
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Static Friction STATIC FRICTION – occurs between two objects that are not _____________. examples: ________________________ Sliding Friction SLIDING FRICTION – occurs when two solid objects _________ over each other examples: __________________________
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Rolling Friction ROLLING FRICTION – occurs between _________ or __________ objects when an object is being moved examples:____________________________________ Fluid Friction FLUID FRICTION – occurs when an object moves ________ or ________ a fluid (all liquids and gases) examples: __________________________
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Gravity
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Mass: The amount of _________ that makes up an object. Does _____ change. Measured in _______. Weight: The force of ______ on an object. Can _______ if gravity changes. Measured in __________
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LAW OF UNIVERSAL GRAVITATION Universal Law of Gravitation – all objects in the universe ___________ each other by the force of gravity. The size of the force depends on the _______ of the objects and the ________ between them.
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Force = ______ x ____________ F = ma What changes
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FALLING OBJECTS The acceleration of a falling object is due to the force of ________ between the ______ and the ______. Near the surface of the earth the acceleration due to gravity is equal to ___________.
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Look at the forces
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Regardless of ______, acceleration due to gravity is always the _____ on Earth. 9.8 m/s 2 Every _______ an object falls it’s velocity increases by 9.8 m/s NO AIR RESISTANCE
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What is Free Fall? 1.An object falling toward Earth with ___________________. 2.An object with only the force of ____________ acting on it. 3.An object falling toward Earth at _______________ 4.An object that will increase its’ velocity __________every single second it falls.
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AIR RESISTANCE Air resistance ______ the downward motion of falling objects (fluid friction). As an object ____, the air resistance gradually becomes _____ to the pull of gravity. When this occurs the forces are _________. There can be no more __________ and the object falls at a constant velocity. This is called the _______________.
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As an object falls with air resistance the force of air increases as the object increases speed. WHEN BALANCED = TERMINAL VELOCITY
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Inertia is the __________ of an object to resist _________. This directly relates to mass, greater _____ = greater _______.
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Newton’s 1 st Law
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According to Newton's first law, an object in motion __________ in motion with the same speed and in the same direction unless acted upon by an ___________ force.
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And really, it’s the force of ________ that brings the rider to a halt.
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Newton's second law (the law of ____________) The acceleration of an object depends on the _____ of the object and the amount of _____ applied.
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Newton's second law 1.Mass- the acceleration _________ as mass increases 2.Force- acceleration _________ as force increases.
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Force= ____ x __________ OR F= ma m=F/a a=F/m
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F= ma F= (____kg) x (___ m/sec 2) F= _____ kg. m/sec 2 or F= ____N (1 Newton= kg x m/sec 2)
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1.Tori applies a force of 20 Newtons to move a bookcase with a mass of 40 kg. What is the acceleration of the bookcase? Practice Answer:
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1.Ollie has a mass of 45 kg. What is his weight in Newtons. (Hint: Acceleration due to gravity = 9.8 m/s 2 ) Practice Answer:
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"For every ______, there is an equal and opposite _______.“ Whenever one object exerts a ______ on a second object, the second object exerts an _____ and ________ force on the first object.
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Forces always come in pairs (equal and opposite action) What are the forces involved with a bird flying?
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The wings of a bird push air __________. The air reacts by pushing the bird _________. Action-reaction force pairs make it possible for birds to fly.
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Momentum A quantity defined as the product of the ______ and the ______ of an object. Momentum can be calculated using: p = (m)(v)
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Momentum The units for momentum are ________ multiplied by _______ per second or kg*m/sec The Law of Conservation of Momentum – states that any time objects ______, the total amount of momentum stays the ______ ~ related to Newton’s 3 rd law
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1.What is the momentum of a 40 kg child who is running straight ahead with a velocity of 2 m/s south. Practice Answer:
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1.Which football player has greater momentum? Player A: Mass = 60 kg; Velocity = 2.5 m/s Player B: Mass = 65 kg; Velocity = 2.0 m/s Practice Answer:
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Pressure: More _______ per unit _____ of a surface. Measured in _____________ The _____ fluid particles in one area the ________ pressure.
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______________ _______________
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Fluids Flow from ____ to ___ pressure. Breathing LP HP LP HP = High Pressure LP = Low Pressure
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Opening a carbonated beverage Fluids Flow from ___ to ___ pressure. HP = High Pressure LP = Low Pressure LP HP Shake up the bottle???? Unscrew the top
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Sipping a straw Fluids Flow from ___ to ___ pressure. Currently the pressure of the fluid in the straw is balanced with the air at the top. Liquid pressure = air pressure HP = High Pressure LP = Low Pressure LP HP When you suck on the straw the air particles above the meniscus get pulled out, therefore lowering the pressure Leaving HP liquid to move up the straw from HP to LP
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Archimedes Principle "Any object, wholly or partly immersed in a _____, is _______ up by a force equal to the ______ of the fluid displaced by the object." The more ______ the object the more likely it is to _____. Rock versus duck????
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Fluid Forces: All fluids exert force in all __________. Fluids include: ______ and ___
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Fluids and Motion Based on Bernoulli’s Principal: _________ in a fluid ________ as the fluid’s _________ increases.
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Lift: _________force on object in fluid Thrust: _______ force exerted by engine Drag: _______ motion of airplane (friction)
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Small Wing = _____ lift / need _____ thrust Large wing: _____ lift / need _____ thrust Air travels fast over top of wing and slower over bottom of wing Slow fluid: ____ pressure Fast Fluid: _____ Pressure
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Fluids flow from _____ to _____ pressure causing the wing to lift Upward Lift
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High Pressure Here
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