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California State Physics Standards Review:. NAME(S):. 1. Motion and Forces: Newton's laws predict the motion of most objects. As a basis for understanding this concept: . a) p53 #50: Light from the sun reaches Earth in 8.3 min. Using the speed of light, how far is the earth from the sun?
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1. Motion and Forces: Newton's laws predict the motion of most objects. As a basis for understanding this concept:
a) p53 #50: Light from the sun reaches Earth in 8.3 min. Using the speed of light, how far is the earth from the sun? b) p53 #53: You and a friend each drive 50. km. You travel at 90. km/hr and your friend travels at 95 km/hr. How long will your friend wait for you in hours and in minutes? c) Another to do: In the 100.-meter dash in the 1988 Summer Olympics, the winning time for the men was 9.92 sec, and for the women was 10.54 sec. What was each of their average speeds? d) Speed & Velocity equations (when a = 0 because F = 0 or in equilibrium): e) Distance, displacement, speed, velocity – which are scalars? vectors? f) What are the four kinematics equations: g) What happens to the speed of an object as it goes up, at the top, & falls back down again? (use the words faster, smaller, zero, positive, negative) h) Fill in the 9 squares at right…
1) Why does a package on the seat of a bus slide backward when the bus accelerates quickly from rest? Why does it slide forward when the driver applies the brakes? Why does it slide to the right when the bus makes a sharp left-hand turn? (Use Newton's 1st Law.) 2) In volleyball, the "spike" is supposed to be fairly quick. However, when "bumping", the player is supposed to move their arms with the ball to cushion it. This has the effect of increasing the contact time. Explain how these actions would effect the acceleration, and therefore the force (using Newton's 2nd Law). 3) Explain how we use Newton's 3rd Law to our advantage to move upward when we jump.
a) Page 191 #58:Using Fg = mg, calculate the weight of a 50.0-kg person: b) Page 191 #58:Sally has a mass of 50.0 kg and the Earth has a mass of 5.98 x 1024 kg. The radius of the Earth is 6.371 x 106 m. Using FG = Gmm/d2 , calculate the force of gravitational attraction between the Earth and Sally. c) Is this the same as the force of gravitational attraction between Sally & the Earth. Why? d) Compare the answers of a and b above; why are they almost the same? What’s the definition of weight?: We now have a way to calculate g on any planet: g = Gm / r2 ... e) Use the Earth's mass & radius provided above to calculate “g” of the earth to 4 sig figs: f) Page 191 #55: Tom has a mass of 70.0 kg and Sally is still 50.0 kg. They are standing 20.0 m apart. What “attraction” does Tom feel for Sally (and Sally feel for Tom)? g) What would have a bigger effect on this force, doubling on of the masses, or halving the distance between them?
a) If I swing around a bucket on a string, which general direction is the force being applied on the bucket? b) Which general direction would the bucket fly off, if the string were to break? For c-e, select up, down, left, or right: c) For the problem at right (top), which direction is the car's force during this turn? d) Which direction is the car’s constantvelocity during this turn? e) Which direction is the car's acceleration during this turn? f) So, based on answers c & d above, which letter answer can be the only correct representation of the force & velocity of the car at top right? g) If the car’s mass is 3000. kg, the car's constant speed in this path is 25 m/s, the radius of the path is 190 meters, what is the car's acceleration? a = h) The car’s period of motion: T = i) Its angular velocity: = j) Its centripetal force: Fc = k) What is the correct letter answer for problem at bottom right?
Work: Work:
4: suitcase being pulled at an angle by a rope 2: Sign in equilibrium 3: Two masses hung by a string suspended from the ceiling by a pulley 5: Piano sliding down an incline plane (ramp at an angle) In all of these problems, what is the net sum of the forces always equal to? (Hint, think Newton’s 2nd law.): Define the word “equilibrium”. (Note – it does NOT necessarily mean the object is not moving! It could simply have zero acceleration, which means its moving at a constant speed!)
Page 559 #45: Object A has a charge of +1.8 x 10-6 C. Object B has a charge of – 1.0 x 10-6 C. They are 0.014 meters apart. What is the static electric force on A? What is the static electric force on B? Why are the answers the same? (Note - This exemplifies the first equation FE = kqq / d2in this Standard; the second equation FG = Gmm / d2 was talked about and used previously in Standard 1e on slide 5.)
2. Conservation of Energy and Momentum: The laws of conservation of energy and momentum provide a way to predict and describe the movement of objects. As a basis for understanding this concept:
Page 309 #77: A physics book is dropped 4.50 meters. What speed does the book have just before it hits the ground? (Realize you don't need a mass to solve this. Why?) What happens to its PE as an object falls? What happens to its KE? Can an object have both at the same time? Can either be negative? Is energy a vector or a scalar? Assuming a mass of 15 kg for the book in the problem above, what was its gravitational potential energy at the top and its kinetic energy at the bottom? Why are they the same?
Before a collision a 25-kg object is moving at +12 m/s. It hits another object of 30.-kg moving at +6.0 m/s. • Calculate the velocity of both objects after the collision if it is completely inelastic (which you should know means they stick together). Use the conservation of momentum only: • pinitial total = pfinal total: • Calculate the velocity of both objects after the collision if it is completely elastic (which you should know means they do NOT stick together. Call the velocity of the 25-kg object after the collision x and the velocity of the other y. Write out a conservation of momentum equation AND the conservation of kinetic energy equation – labeling both. Solve both equations for y (they will have x in them) and graph them on your calculator & find the intersection: • pinitial total = pfinal total: • KEinitial total = KEfinal total:
3. Heat and Thermodynamics: Energy cannot be created or destroyed, although in many processes energy is transferred to the environment as heat. As a basis for understanding this concept:
4. Waves: Waves have characteristic properties that do not depend on the type of wave. As a basis for understanding this concept:
Interference: Reflection: Diffraction: Refraction: Beats: Doppler effect: Polarization:
5. Electric and Magnetic Phenomena: Electric and magnetic phenomena are related and have many practical applications. As a basis for understanding this concept:
Remember: When in parallel, voltage is the same so write the volts. When in series, current is the same so write the amps. There are LOTS of circuits on the CST’s. Analyze the circuit at left below, assuming each resistor is 5 Ohms, and the voltage is 120V. (Do it on paper and scan it in!) ALSO, find the power through each of the resistors in the original picture.
What does a capacitor do? • What is the structure of a capacitor? • Give an example of where a capacitor is used? • How do you charge a capacitor? • How do you discharge a capacitor? • What is the difference between a capacitor and a battery? • What is the formula for capacitance? • A semi-conductor is a substance that does / does not (choose one) conduct charge as efficiently as a conductor. • In the last sentence of the first paragraph on page 788, it says … • When several transistors are connected together to perform logic operations, ... they act as fast ________ (turning specific parts of a circuit on or off very quickly, like in computers & calculators). • But “rather than” that transistors are used as __________ in almost every electronic instrument.
Remember they show the way a “positive test charge” wants to move! Explain what the E field around a positive charge looks like? (Let's call this field A) Explain what the E field around a negative charge looks like? (Let's call this field B) What force (in general) would a positively charged proton feel if in electric field A? What force (in general) would a positively charged proton feel if in electric field B? What force (in general) would a negatively charged electron feel if in electric field A? What force (in general) would a negatively charged electron feel if in electric field B? If the strength of the E fields were 6.3 x 105 N/C, what exact force would a proton (q = + 1.602 x 10-16 C) feel in either of these fields? If the strength of the E fields were 6.3 x 105 N/C, what exact force would a electron (q = 1.602 x 10-16 C) feel in either of these fields? (Use F = q E) What must be the left and right charges in the top E field shown at right? What must the left and right charges be in the bottom E field shown at right? How would the bottom E field change of both of those charges were opposite of that? p586 #75a: A lead nucleus has the charge of 83 protons, so q = 83 x 1.602 x 10-16 C. What is the magnitude & direction of the electric field at 10 x 10-10 meters from the nucleus? (Use E = k q / d)
What are the only three elements that can become magnetized? How do they become magnetized? (“Domains” are technically electron-spins, but Standards-based tests often simply say a domain is “the motion of the charged particles inside the metal.”) What 2 ways can you create a magnetic field? (Think of Bill Nye.) In the top diagram at right, which hand is being used? Is the thumb pointing in the direction of the "electron-flow" current, or the conventional current? What do the blue lines tell you about the magnetic field? Add even more arrows in all over those circles. In the bottom figure at right, (a) What is the direction of the magnetic field inside the loop? (b) What is the direction of the magnetic outside the loop? Fill in the blank: A current can cause a magnetic field, and a changing magnetic field can cause a _______.
Look in the tan boxes on pages 653 AND 657 in your text to find two formulas for determining the force on a particle in a magnetic field: (Also tell what each letter stands for!) F = F = Define a plasma: Like p368#54: Some of the mercury atoms in a fluorescent lamp are in the gaseous form, others are in the form of plasma. How can you distinguish between the two? Standard 5n is not covered on the CST-STAR exams. A _________ converts kinetic energy into electrical energy, and a _________ converts electrical energy into kinetic energy.