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Unit 6: Motion and Forces 2015 1 Stevens Unit 6: Motion and Forces VOCABULARY: Term Definition Motion Speed Distance How much ground an object has covered during its motion; how far apart two points are Velocity Frame of reference Acceleration Vector Force Net Force Inertia Newton’s 1st Law of Motion (Law of Inertia) objects at rest remain at rest, and objects in motion remain in motion with the same velocity, unless acted upon by an unbalanced force Newton’s 2nd Law of Motion the acceleration of an object increases with increased force and decreases with increased mass Newton’s 3rd Law of Motion Equation (if applicable) or example Unit 6: Motion and Forces 2015 2 Stevens Gravitational Force Section 1: Key Ideas: Analyze the motion of an object in terms of its position, velocity and acceleration as functions of time Solve problems involving distance, velocity, speed and acceleration Create and interpret graphs Vocabulary: Motion - Displacement Speed - Acceleration Velocity - Vector Distance Frame of Reference Motion _______________________________________________________________________ _______________________________________________________________________ relies on a frame of reference or something assumed to be stationary _______________________________________________________________________ o i.e. – you may be stationary as you sit in your seat, but you are moving 30 km/sec (≈19 mi/sec) relative to the Sun Frame of Reference (Reference Point) _____________________________________________________________________________ none are truly stationary relative to all others – what is not moving in one is moving in another Task: o Using your body as the frame of reference, describe your classmate’s motion as s/he walks to the classroom door. How does your frame of reference impact your description compared to that of others? __________________________________ __________________________________________________________________ How does frame of reference explain why people thought the Earth was in the center of all celestial bodies? _________________________________________ __________________________________________________________________ Speed Unit 6: Motion and Forces 2015 3 Stevens ___________________________________________________________________________ a measure of how fast something moves, or the distance it moves, in a given amount of time Formula: s = d (distance) t (time) typically expressed in units of m/s is considered _______________ when taking into account the total distance covered and the total time of travel is considered __________________when it does not change is considered _______________________ when it represents a specific instant in time What is the ball’s speed? ___________________________________________________ Practice problems – Speed: 1. If you walk for 1.5 hours and travel 7.5 km, what is your average speed? 2. Calculate the speed of a bee that flies 22 meters in 2 seconds. Draw the Speed-Distance-Time Triangle Draw the distance time graph: 1. What is the speed from A – B? ________________________________________ 2. What is the speed from B-C? __________________________________________ 3. What is the speed from C-D? __________________________________________ 4. What is the students average speed? _____________________________________ Unit 6: Motion and Forces 2015 4 Stevens Underneath each graph, describe what’s happening? Thought question: Two birds perched directly next to each other, leave the same tree at the same time. They both fly at 10 km/h for one hour, 15 km/h for 30 minutes, and 5 km/h for one hour. Why don’t they end up at the same destination? ______________________________________ ______________________________________________________________________________ Velocity _______________________________________________________________________ _______________________________________________________________________ is considered ____________________when speed and direction do not change changes as ________________________________________________ changes is a vector can be combined o Example If you are walking at a rate of 1.5 m/s up the aisle of an airplane that is traveling north at a rate of 246 m/s, your velocity would actually be 247.5 m/s north What is the formula for velocity? What is this similar to? _________________________ ________________________________________________________________________ Unit 6: Motion and Forces 2015 5 Stevens Vector: ______________________________________________________________________________ drawn as an arrow which shows direction and magnitude (length of arrow) o consists of two parts: tail and head (draw an example) Combining Vectors: can be combined/added What is the total velocity for each of the people/animals on the conveyor belt? _____________________ ________________________ ___________________ Acceleration: ____________________________________________________________________________ is a vector occurs when something is speeding up (+), slowing down (-), or changing direction Formula: a = vf – vi (where vf is final velocity, and vi is initial velocity) t(time) typically expressed in units of m/s2 is always changing when traveling in a circle – centripetal 1. Is the ball accelerating? ________________________________________________ 2. Describe the car’s acceleration: ______________________________________________ ________________________________________________________________________ Unit 6: Motion and Forces 2015 6 Stevens 3. What if I am traveling in my car at 60mph North constantly? What would my acceleration be? __________________________________________________________ Practice Problems – Acceleration: 1. Tina starts riding her bike down a hill with a velocity of 2 m/s. After six seconds, her velocity is 14 m/s. What is Tina’s acceleration? 2. A motorcyclist goes from 35 m/s to 20 m/s in five seconds. What was his acceleration? Momentum: ________________________________________________________________________________ is a vector the product of an object’s mass and velocity Formula: p=mv (p is momentum, m=mass, v=velocity) typically expressed in units of kg·m/s _________________________________________________________________________________ makes an object harder to stop or change direction as it increases can be transferred is conserved Practice Problems – Momentum: 1. What is the momentum of a 7.3 kg bowling ball moving at 8.9 m/s? Unit 6: Motion and Forces 2015 7 Stevens 2. At a velocity of 8.5 m/s, Tim moves down a hill on an inner tube. If his mass is 59 kg, how much momentum does he have? Practice: A helicopters speed increases from 25 m/s to 60m/s in 5 seconds. What is the acceleration of this helicopter? How far will you travel if you run for 10 minutes at 2.0m/s? How much time would it take for the sound of thunder to travel 1,500 meters if sound travels at a speed of 330m/s? At a velocity of 10 m/s NE, Sadie moves down a mountain on her snowboard. If her momentum is 460 kg·m/s, what is her mass? Section 2: Forces and Newton’s 3 Laws of Motion Key Ideas Interpret and Apply Newton’s 3 Laws of Motion Vocabulary Inertia 1st Law 2nd Law 3rd Law Friction Tension - Force - Net force - Applied force - Normal force - Air Resistance - Spring Force: ____________________________________________________________________________ typically measured in Newtons (kg•m/s2) Unit 6: Motion and Forces 2015 8 Stevens is a vector can be combined to predict motion net force Net force: ____________________________________________________________________ Types of Forces: Contact Forces o Applied o Normal o Friction o Air Resistance o Tension o Spring Applied Force: Non-Contact Forces o Gravity o Electromagnetic any push or pull on an object created from another source (person, animal, another object, etc.) Normal Force: the support force exerted on an object directly related to weight (gravity) consequence of Newton’s 3rd Law _____________________________________________________________________________ Draw and label the pictures Friction: exerted by a surface as an object moves across it or attempts to move across it ___________________________________________________________________________ depends on the type of surfaces and the normal force (weight) Unit 6: Motion and Forces 2015 9 Stevens Air Resistance: ____________________________________________________________________________ acts upon objects as they travel through the air ___________________________________________________________________________ most noticeable for objects traveling at fast speeds Tension: force that is transmitted through a string, rope, cable or wire when it is _______________ tight by forces acting from opposite ends directed along the length of the wire and ______________ equally on the objects on the opposite ends of the wire Spring: ________________________________________________________________________________ for most springs, the magnitude of the force is directly proportional to the amount of stretch or compression of the spring Gravity: _____________________________________________________________________________ factors: distance – increased distance less gravitational pull or vice versa mass – increased mass more gravitational pull or vice versa Why does the force of gravity have more of an impact on holding our solar system together compared to holding the parts of an atom together? _________________ ___________________________________________________________________ Electromagnetic Force: Unit 6: Motion and Forces 2015 10 Stevens force that moving charges exert on one another results from the repulsion of like charges and the attraction of opposites Vector Review: a quantity that has both direction and magnitude (size) drawn as an arrow which shows direction and magnitude (length of arrow) o consists of two parts: tail and head Draw the vectors. Then describe the direction and relative magnitude of each ball based on the vector. Combining Vectors Review: can be combined/added to help determine net force o the overall force acting on an object when all of the forces acting on it are combined o Draw the picture and determine the net force. Free Body Diagrams: visuals that help show net force o use a square and draw all forces acting on the object. o remember size and direction of vector arrows are important! Unit 6: Motion and Forces 2015 11 Stevens o Draw the diagram and determine the net force. Determine the net force: Fnorm = 10 N Ffric = 5 N Fapp = 15 N Fgrav = 10 N Net force: __________________________ Net force:_____________________ Newton’s Laws of Motion: Newton’s 1st Law of Law of Inertia: objects at rest remain at rest, and objects in motion remain in motion with the same velocity, unless acted upon by an unbalanced force also considered the Law of Inertia How is this illustrated when riding in a car? Can you think of other experiences where this is illustrated? _________________________________________________________ ________________________________________________________________________ Unit 6: Motion and Forces 2015 12 Stevens Inertia: the resistance of an object to a change in the speed or the direction of its motion ________________________________________________________________________ Which has more inertia: a car or a person? Why? ____________________________ ________________________________________________________________________ Newton’s 2nd Law of Motion: the acceleration of an object increases with increased force and decreases with increased mass _________________________________________________________________________________ Formula: F = ma (or a = F/m) Practice Problems – 2nd Law: 1. What net force is needed to accelerate a 24 kg dogsled to a rate of 3 m/s2? 2. A 1.5 kg object accelerates across a smooth table at a rate of 0.5 m/s2? What is the unbalanced force applied to it? Newton’s 3rd Law of Motion: states that every time one object exerts a force on another object, the second object exerts a force that is equal in size and opposite in direction back on the first object Can you think of any experiences/examples where this is illustrated? ________________ ________________________________________________________________________ Section 3: Gravitational Force Key Ideas Unit 6: Motion and Forces 2015 13 Stevens o Explore how the gravitational force between two objects depends on their masses and the distance between them. Vocabulary o Gravity o Gravitational Constant Law of Universal Gravitation: Where: Fg = Force of Gravity G = the gravitational constant (6.67 x 10-11 N *m2/kg2) M1= Mass of object 1 M2 = Mass of object 2 d = distance between two objects Gravity ____________________________________________________________________!!!!!! Unit 6: Motion and Forces 2015 14 Stevens SECTION 3: Key Ideas: • • What are Synthesis (creating) Decomposition (separating) Unit 6: Motion and Forces 2015 15 Stevens • Combustion (burning) • Displacement/Replacement (switching) SYNTHESIS (CREATING) • ________________________________________________________________________ • Ex: Synthesis of Carbon Dioxide 2CO(g) + O2(g) → 2CO2(g) DECOMPOSITION (SEPARATING) • _______________________________________________________________________ • Ex: Electrolysis of water to make hydrogen and oxygen • 2 H2O ---> 2 H2 + O2 COMBUSTION (BURNING) • ______________________________________________________________________ • Oxygen reacts with another element or compound to form water (H2O), carbon dioxide (CO2) and heat • _______________________________________________________________________ Unit 6: Motion and Forces 2015 16 Stevens DISPLACEMENT/REPLACEMENT (SWITCHING) • Two types: Single replacement and double replacement • Single replacement (substitution): ___________________________________________________________________________ _________________________________________________________ • • Ex: Zn + 2 HCl → ZnCl2 + H2 • Ex: Double Replacement: _______________________________________________ __________________________________________________________________ • Ex: AgNO3 + HCl → AgCl + HNO3 • Ex: Fe2O3 + HCl → FeCl3 + H2O CHEMICAL VS NUCLEAR RXN: Chemical Reaction • Atoms are rearranged, and chemical bonds are broken and reformed • New substance is formed Nuclear Reaction • __________________________________ • Involves at least two nuclei, where one has to have all its electrons removed, by bringing it to very high temperatures. Why must the electrons be removed? • A neutron is then “slammed” into another nucleus, causing the nucleus to break apart (fission) or combine to create a new nucleus (fusion) C6H12O6 + 6O2 6CO2 + 6H2O + energy (respiration)