Physics Final Exam Review 2012 - WW-P High Schools

Physics Final Review Problems 2012

Physics Final Exam Review 2012 Chapter

Topic

Formulae

2-3, 5-6 MOTION/KINEMATICS: const velocity: v= Δd/Δt, xf=x0 +vt /2D MOTION acceleration: a=Δv/Δt accelerated motion: vf= v0+at vf2=vi2+2ad, xf=x0+v0t + ½ at2 4-5 NEWTON’S LAWS F = ma, Fg = mg, Ff = µFn /STATIC EQUILIBRIUM 9

MOMENTUM

10-11 ENERGY:

p=mv; F∆t = mΔv (impulse/momentum) mivi = mfvf (conservation of momentum) work W= Fxd, potential energy PE= mgh, P=W/t, kinetic energy KE= 1/2mv2

6, 8

CIRCULAR/ ROTATIONAL MOTION: v=(2πr)/T, T=1/f; Ac=v2/r, Fc=mAc, τ = Fr

7

UNIVERSAL GRAVITATION:

20

ELECTROSTATICS

21

ELECTRIC FIELDS

Fg = Gm1 m2/ r2 ; G = 6.67x10-11Nm2/kg2

Fe = K q1 q2 / r2; K=9.0x109 Nm2/C2 V= Potential Energy/Unit Charge (J/C)

22-23 DC CIRCUITS current I = charge/time Ohm’s Law—I = V/r; Power P=IV, P=I2R, P=V2/R 16-18 OPTICS


Kinematics x(t) = x o + vt

€

€ € €

€ € € € €

€ €

€ €

€ € € € € € € €

1 x(t) = x o + v o t + at 2 2 v(t) = v o + at v(t) 2 = v o2 + 2a(Δx) Freefall: a = g = ±9.8m /s2 Dynamics Fnet €a = m FEarthonobject = mg F1on 2 = −F2on1 Fs // = µsN Fk // = µk N 2D Motion d = vt 1 h = gt 2 2 Circular Motion v2 ac = r Fc = mac Static Equilibrium Στ = 0N • m F1d1 = F2 d2 Momentum p = mv I = FΔt FΔt = mΔv m1v1i + m2v 2 i = m1v1 f + m2v 2 f m1v1i + m2v 2 i = (m1 + m2 )v f Energy W = Fd cos θ 1 K = mv 2 2

€ € €

Electrostatics and Electric Fields

€

Fq1 onq 2 = k

q1q2 d2

DC Circuits

€

1 I = ΔV R P = IV =

€ €

m2 k = 9x10 N 2 C

€

V2 = I 2R R

Series Circuit ITotal = I1 = I2 = I3 = ... ΔV = V1 + V2 + V3 + ...

€

RTotal = R1 + R2 + R3 + ...

€

Parallel Circuit ITotal = I1 + I2 + I3 + ...

€

ΔV = V1 = V2 = V3 = ... € €

€

€ € €

€

U g = mgy 1 U s = kx 2 2 ΔU int = Fs // d W P= t

1 RTotal

=

1 1 1 + + + ... R1 R2 R3

Optics 1 1 1 = + f do d i h d M = i =− i ho do n1 sin θ i = n 2 sin θ r

9


*Note: these problems are a general overview of what we have learned. Going through your notes, textbooks, old quizzes, old tests, and possibly even some labs will aide in your studying for the final exam.

Kinematics Make sure you know how to: a) Draw a motion diagram for a moving object b) Determine the direction of acceleration using a motion diagram 1. Are you moving while sitting on a train that is leaving the station? 2. Describe the point-like model of a real object. Explain why we can use this model to describe the motion of a real object. 3. What is the difference between initial position, final position, distance, displacement, and path length? 4. The position-vs-time graph for a moving object is a straight line with a slope equal to -15.0 m/s. Explain what this means about the motion of the object. 5. Give an example in which an object with negative acceleration and is speeding up. Give an example in which an object with positive acceleration is slowing down. 6. A car’s motion with respect to the ground is described by the following function: X(t) = (-48 m) + (12 m/s)t + (-2 m/s2)t2 Determine the car’s position and velocity at time zero. Also, determine its acceleration. At what time (if any) does the car’s velocity become zero? 7. While driving along a flat stretch on the highway, there is a policeman parked behind a bush. As you drive by he uses his speed gun to track your speed over a period of 10 seconds. The data he includes in his report is given in the table below. Time (s) 0 2 4 6 8 10

Velocity (mph) 45 60 78 94 108 125

a) b) c) d) e)

Plot a velocity vs time graph. What type of relationship is displayed on the graph? What is the equation of the graph? Using the graph, determine the displacement of your car after 8 seconds. Plot an acceleration vs time graph.


8. A car goes from a stop to 100 km/hr in 10 seconds. It then travels at that rate for the following hour. After that hour it brakes to a stop in 15 seconds. a) What is the car's rate of acceleration during the 1st 10 seconds? b) What is the total distance (in meters) that the car travels during the trip? c) What is the car's average velocity during the whole trip? 9. If you throw a tennis ball straight up in the air with a velocity of 30m/s, how long will it take to come back to the ground? What is the acceleration of the ball when at the tippy-top of the flight? 10. Ashleigh and Rachael are bored with attending choral lessons inside the high school and decide instead to practice their singing while skydiving. They pick their new favorite song, Ring of Fire by Johnny Cash, and get into the airplane. Ignore air resistance. a) Sketch the situation b) Draw a motion diagram c) If Ring of Fire is 2 min 36 sec long, at what altitude do they have to fall from in order to finish the song right before reaching the ground? d) What will their final velocity be right before reaching ground? 11. Chris is playing in a lacrosse game against South’s rival North. He catches a pass and has a breakaway against the goalie. His initial speed is 2 m/s and he accelerates at a rate of 4 m/s2 for 3.4 s until he shoots the ball. a) Sketch the situation b) Draw a motion diagram c) How fast is he going when she releases the ball? d) How far did he run while accelerating?

Forces and Newton’s Laws Make sure you know how to: a) Identify a system, construct a force diagram for it, and use the force diagram to apply Newton’s second law. 12. You slide toward the right at decreasing speed on a horizontal wooden floor. Choose yourself as the system and list external objects that interact with and exert forces on you. 13. A book bag is partially supported while hanging from a spring scale and also sitting on a platform scale. The platform scale reads about 36 units of force and the spring scale reads about 28 units of force. What is the magnitude of the force that Earth exerts on the bag? 14. Why do you need to keep pushing a grocery cart in a store in order to keep it moving?


15. An elevator in a tall office building moves downward at constant speed. How does the magnitude of the upward force exerted by the cable on the elevator compare to the magnitude of the downward force exerted by Earth on the elevator? Explain your reasoning. 16. Three friends are arguing about the type of information a bathroom scale reports. Eugenia says that it reads the weight of a person, Alan says that it reads the sum of the forces exerted on the person by Earth and the scale, and Mike says that the scale reads the force that the scale exerts on the person. Who do you think is correct? Why? 17. Identify third law force pairs for the following interactions: A rollerblader and the floor, a volleyball player and the volleyball, and a speeding up car’s tires and the road. 18. Explain how an airbag reduces the stopping force exerted on the driver of a car. 19. Draw all of the forces for the following rocks. no acceleration moving at constant speed moving in a circle around post

20. Alex’s car (900 kg) stalls 10 m from the Amwell Road parking lot. Alex gets two of his strong physics friends, Sam and Tim, to help him move the car. The 3 students push horizontally with a force of 500 N each. a. Sketch the situation, circle the object of interest b. Draw and label a Free Body Diagram for the object of interest c. Solve for any of the forces that you can in the FBD d. What is the acceleration of the car? e. How long does it take them to reach the parking lot?

Two Dimensional Motion 21. Michelle stands on the Millstone River Bridge kicking stones into the water below. A) If Michelle kicks a stone with a horizontal velocity of 3.50 m/s, and it lands in the water with a horizontal distance of 5.40 m from where Michelle is standing, what is the height of the bridge? B) If the stone had been kicked harder, how would this affect the time it would take to fall?


22. Jake drops a cherry pit out the car window 1.0 m above the ground while traveling down the road at 18 m/s. a) How far, horizontally, from the initial dropping point will the pit hit the ground? B) Draw a picture of the situation. C) if the car continues to travel at the same speed, where will the car be in relation to the pit when it lands? 23. A boy on a 250 m high tower throws a ball 100 m away horizontally. a) How long (in seconds) does the ball take to hit the ground? b) How fast did the person throw the ball horizontally?

Circular Motion 24. Use your understanding of Newton’s laws to explain why you tend to slide across the car seat when the car makes a sharp turn. 25. A 13 g holiday ornament is attached to a 0.93 m string. The stopper is swung in a horizontal circle making one revolution in 1.18 s. Determine the force exerted by the string on the stopper. 26. A 5 kg metal ball is swung in a circle attached to a 1 meter chain. The ball is traveling at 5 m/s. a. Determine the centripetal acceleration of the ball b. Determine how hard you need to pull on the chain to maintain this rotation.

Static Equilibrium 27. A 1 m long 10 kg shelf is attached to the wall by a hinge so it can collapse and hide away. When you need it you can hang it by the other end with a chain from the ceiling. Currently, the shelf is holding 5 kg worth of books 0.6 m away from the wall, a pair of 2kg glasses 0.9 m away from the wall, and your 12 kg laptop 0.3 m away from the wall. The maximum force of tension that the chain can withstand before breaking is 120 N. a) Will it be able to support all of these objects? b) What is the force of tension in the chain? c) If it cannot support the objects, what can we do to provide additional support for the shelf? 28. A meter stick (100 cm) is supported at the 50 cm mark. A 20 g mass sits on the 20 cm mark, a 40 g mass sits on the 40 cm mark, a 60 g mass sits on the 60 cm mark, and an 80 g mass sits on the 80 cm mark. Where would a 150 g mass need to be located in order to balance the system? (cm) 29. Fred (95kg) sits 1.25 meters away from the middle of a seesaw. How far away should another person (75kg) sit in order to balance out the see saw?


Impulse and Momentum Make sure you know how to: a) construct a force diagram for an object b) use kinematics to describe an object’s motion c) understand the difference between constant and conserved for various systems d) Use impulse-momentum bar charts 30. Two identical cars are traveling toward each other at the same speed. One of the carts has a piece of modeling clay on its front. The carts collide, stick together, and stop; the momentum of each cart is now zero. If the system includes both carts, did the momentum of the system disappear? Explain your answer. 31. As a bullet enters a block, the block exerts a force on the bullet, causing the bullet’s speed to decrease to almost zero. How can we use conservation of momentum to analyze this situation? 32. When a meteorite hits the Earth, the meteorite’s motion apparently disappears completely. How can we claim that momentum is conserved? 33. Robin Hood has a mass of 35kg and shoots a 0.1kg arrow at a speed of 150m/s, causing him to move in the opposite direction. a. Sketch the before and after situations b. What is the recoil speed of the archer? 34. A 0.3-kg tennis ball traveling at 15 m/s is returned by Daria. It leaves her racket with a speed of 44 m/s in the opposite direction from which it came. a. Sketch the situation. b. If the racket and the ball are in contact for 0.05 s, calculate the average force the racket exerts on the ball. 35. A carnival game requires you to knock over stuffed clowns at the NJ shore. You are given the option of picking a ball that is very bouncy or a big lump of clay. Both options have the same amount of mass. Assume you can throw them with equal speed and accuracy and you only get one throw. Which option would you choose? Why? 36. A 40 kg skater traveling at 4 m/s overtakes a 60 kg skater traveling at 2 m/s in the same direction and collides with her. a. Sketch the before and after situations b. If they remain in contact after the collision, what is their final velocity? 37. Andrew, who has a mass of 60.0 kg is riding at 25 m/s in his sports car when he must suddenly slam on the brakes to avoid hitting a dog crossing the road. He is wearing his seatbelt that brings his body to a stop in 0.400 s. a. What average force did the seatbelt exert on him? b. If he had not been wearing her seatbelt, and the windshield had stopped his head in 0.001 s, what average force would the windshield have exerted on him? c. How many times greater is the stopping force of the windshield than the seatbelt?


Work and Energy Make sure you know how to: a) Choose a system and the initial and final states of a physical process b) Use Newton’s second law to analyze a physical process c) Use kinematics to describe motion d) Use work and energy bar charts 38. Describe two processes where an external force is exerted on a system object and there is no work done on the system 39. When we use energy conservation ideas, how do we incorporate the force that Earth exerts on an object? 40. Thomas and Nikola are running towards each other at high speeds. They collide and stop. Where did their kinetic energy go? What happened to their momentum? 41. Why is it important to choose the system of interest before attempting to analyze a process? 42. Albert and Isaac decide to go hiking and both weigh 60 kg. The mountain they choose to climb is 1600 m high. It takes Albert 15 minutes to reach the top, and it takes Isaac 25 minutes. If they both climb straight up, who does more work climbing the mountain? Why? How much power does each student generate? 43. If an object’s speed increases by a factor of 5, what factor would the kinetic energy increase by? 44. In Metropolis, the comic book hero Superman uses his incredible strength to save the lives of countless ordinary citizens. One day, the braking system on a passenger bus fails when the bus is 50 m away from a busy intersection. The bus is moving towards the intersection at 5 m/s. If Superman exerts a force of 300 N on the bus, which has a mass of 1000 kg, will he be able to stop the bus before it reaches the busy intersection? 45. Describe a real-life situation in which an external force does the following: a. Positive work on a system b. Positive work on a system but with a value that is less than that in part (a) c. Negative work on a system d. Zero work, even though an object in the system moves. 46. A 4 kg. bowling ball is raised 15 m. to the top of a ramp. It is released from rest and travels to the bottom. a) How much force is exerted by gravity on the ball when it is at the top of the ramp? b) How much PE does the ball have when it is at the top of the ramp? The bottom of the ramp? c) How fast is it traveling when it reaches the bottom (ignore friction).

Universal Gravitation 47. Determine the gravitational force between two objects that are 100 km. apart if one has a mass of 100 kg and the other has a mass of 6.5 x 1019 kg.


Electrostatics/Electric Fields Make sure you know how to: a) find the force that one charged object exerts on another charged object b) apply the concept of electric field to understand electric interactions c) explain the difference between the internal structure of electric conductors and non-conductors. d) Know the difference between charging by conduction and charging by induction. 48. Summarize the particle model of charging by direct contact. 49. You have a charged electroscope on your desk. How can you decide whether it is positively or negatively charged? 50. You have two identical small metal foil bits hanging on threads. You charge one of them, and then touch them together. Then you place them at a distance d from each other and measure the force with which they repel each other. Qualitatively, how will the force change if you keep the distance the same but after charging touch one of the bits with your hand? What assumptions did you make in coming up with your answer? 51. Are electrostatic interactions the same as magnetic interactions? What is similar? What is different? 52. Determine the electrical force between two objects that are 100 km. apart if they have a charge of one Coulomb and six Coulombs respectively. 53. Two charged particles, A and B, are near each other, but not touching. A

B

a. What will happen to the force exerted on each particle if the charge on A is doubled? b. What will happen to the force exerted on each particle if the charge on B is doubled? c. What will happen to the force exerted on each particle if the charge on each particle is doubled? d. What will happen to the force exerted on each particle if their separation distance is doubled? e. What will happen to the force exerted on each particle if the charge on A is doubled and their separation distance is cut in half? 54. A metal sphere has a mass of 1.22 kg and carries a charge of -3.34 x 10-9 C. Determine the size of the charge required to levitate the sphere 1.00 cm above the charge. 55. Use the ideas of shielding and electric fields to explain why you are safe in your car if there is lightning nearby.


DC Circuits Make sure you know how to: a) Distinguish between series and parallel circuits b) Solve complex circuit problems using Ohm’s law c) Draw circuit diagrams using the proper symbols 56. What condition(s) are needed for electric charge to travel from one place to another? In other words, what makes a working circuit? 57. You have two resistors, R1 and R2 with R1 > R2. You first connect them in parallel to a battery; then connect them in series to a battery. Compare the total resistance of the parallel and series arrangements with the resistance of each individual resistor. 58. In what direction do electric charges move in a circuit and in what direction do they move inside a battery? 59. A complex circuit contains a 90 V battery followed by a 50 Ω resistor, followed by a parallel branch containing 40 Ω, 50 Ω, and 60 Ω resistors. The final resistor is 70 Ω. a) RT = ? b) Icircuit = ? c) Vparallel branch = ? 60. A 57V battery is connected to the following circuit. Find the following: a. Rtotal = ? b. Itotal = ? c. VR1 = ? d. IR2 = ? Given: R1 = 15Ω R2 = 40Ω R3 = 20Ω R4 = 20Ω R5 = 30Ω R6 = 30Ω V = 57V

R6

R5

R3

R4

R2 R1

57V 61. Draw schematic diagrams for the following circuits: A battery attached to 3 resistors all in 2 resistors and a light bulb in series with parallel with an open switch on one two batteries branch


Optics 62. Compare and contrast concave mirrors, convex mirrors, and plane mirrors in terms of image formation. 63. Compare converging and diverging lenses. What are applications of each type of lens? 64. Compare convex and concave mirrors. What are applications of each type of lens? 65. What is reflection? What is refraction?