STRAIGHTER LINE- GENERAL PHYSICS EXAM 1, Exams of Social Sciences

Download STRAIGHTER LINE- GENERAL PHYSICS EXAM 1 and more Exams Social Sciences in PDF only on Docsity! STRAIGHTER LINE: GENERAL PHYSICS EXAM 1 Which of the following statements related to conversion factors is false? A. A conversion factor is the ratio of the given unit to the required unit. B. A conversion factor does not necessarily convert to standard SI units. C. The expression 60 min / hour is an example of a conversion factor. D. The value of a conversion factor is essentially 1. - Answers-A What are SI units? A. Standard Index units of measurement B. Units from the old English measurement system C. International time units D. Systeme International units of measurement - Answers-D An SI unit is a Systeme Internacionale unit. In most cases, an SI unit is an mks unit or is derived from mks units. Suppose you are told that 15 quarts (qt) = 14.2 liters (L). What is the conversion factor you would use to convert from quarts to liters? What is the conversion factor you would you use to convert liters to quarts? A. quarts to liters: 14.2 L / 15 qtliters to quarts: 15 qt / 14.2 L B. quarts to liters:15 qt + 14.2 Lliters to quarts: 29.2 qt / L C. quarts to liters: 15 qt / 14.2 Lliters to quarts: 1.06 qt / L D. quarts to liters: 15 qt • 14.2 Lliters to quarts: 213 qt / L - Answers-A An object travels a distance d with acceleration (a) over a period of time (t) according to the equation: d=(1/2) at^2. After 2.3 seconds with an acceleration of 9.8 m/s, how far does an object travel? a. d=(1/2)at^2=(1/2)(9.8m/s^2)(2.3s)^2= 26m b. d=(1/2)at^2=(1/2)(9.8m/s^2)(2.3s)^2= 11m c. (1/2)at^2=(1/2)(9.8m/s^2)(2.3s)^2 = 26m/s d. None of the above. - Answers-A Which of the following uses a derived SI unit measurement? a. time b. speed c. distance d. mass - Answers-b The circumference of a circle is defined by the equation C=2πr, where π=3.14. Suppose that r = 0.0347 m. Which of the following correctly shows the circumference of the circle? a. C = 0.378 m2 b. C = 0.237916 m c. C = 0.2 m d. C = 0.218 m - Answers-d Which of the following statements about SI distance units is not correct? a. Both a meter and a kilometer are SI units. b. A mile is not an SI unit. c. A meter currently has a universal unit definition. d. Converting a meter to feet is an example of a conversion involving two different SI units for distance. - Answers-d Which of the following does not explain the use of SI units in physics? a. SI units have been universally accepted as the standard by the scientific community. b. SI units are more difficult to manipulate than old English system units (such as the foot and the pound). c. Physicists are able to measure complicated quantities using mks units. d. SI units are arbitrarily defined. - Answers-B Vectors A→ ,B→ and C--> are shown in the figure. Which of the following is correct? a. C→=A→−B→ b. C→=B→−A→ c. C→=A→+B→ d. C→=∣A→∣+∣B→∣ - Answers-a If C→=A→+B→ then the magnitude of C→ or ∣C→∣, is the sum of the magnitudes of A→ and B→ or A→+B→, a. When A and B are in the same direction. b. When A and B are in the opposite direction. c. under no circumstances. d. Answers A and B. - Answers-a In order to understand vectors, you must understand some basic trigonometry. Which of the following correctly relates x,y,t and θ? - Answers-c. x=t cos 0; y=t sin 0 tan0= y/x;t= sq (x^2+y^2) If C→=A→+B→, then the magnitude of C→, or ∣C→∣, is the sum of the magnitudes of A→ and B→, or ∣A→∣+∣B→∣ - Answers-False Suppose you have $100 that you need to convert to Danish kroner. The conversion rate that day is 5.732 Danish kroner for one American dollar. The business that converts your money charges you a flat fee of 50 Danish kroner for the transaction. Use your knowledge of significant figures to decide which of the following shows the correct amount of Danish kroner that you should receive. A. 573.2 Danish kroner B. 500 Danish kroner C. 523.2 Danish kroner Consider the vectors A→ and B→ shown in the picture. Think about an example where B→ represents the force applied to a wrench, and A→�→ represents the wrench. Which of the following statements about these vectors is not correct? - Answers-b. To unscrew a bolt, a force in the direction parallel to the wrench must be applied. This force is a scalar with a magnitude B. For each of the following diagrams estimate A→×B→�→×�→. Which will result in the largest vector pointing out of the screen? Note that A→�→ and B→�→ each have the same magnitude in all of the figures. - Answers-c. Find the cross product of the following two vectors: A→=3i^−2j^ B→=2i^−j^ - Answers-c. 1k^ Suppose you are trying to solve for the cross product of two vectors in the XY-plane that are defined as A→=Axi^+Ayj^ and B→=Bxi^+Byj^ Which of the following statements about these vectors is not correct? - Answers- b.A→×(B→+C→) =( A→×B→)×(A→×C→) Two vectors in the XY- plane are defined by the equations: A→=2i^−2j^B→=3i^+j^�→=2�^−2�^�→=3�^+�^ Which of the following answer choices related to the cross product of these two vectors or the measure of angle θ� between the two vectors is not correct? - Answers-d. θ=45∘ Two vectors in the XY-plane are defined by the equations A→=2i^+5j^B→=−2i^+j^ Suppose you are asked to find the dot product of the two vectors, the cross product of the two vectors, and the measure of the angle θ between the two vectors. Which of the following statements related to any of these operations is not correct? - Answers-a. The angle θ� between the two vectors is 42∘. Look at the plot that shows the position of a falling ball as a function of time, t. Which of the following statements about this event is not correct? - Answers-B. The greatest magnitude of the average velocity occurs from t1 to t2. The graph illustrates the motion of an object. Which of the following statements is correct? - Answers-A. The acceleration of the object increases with time. One of the simplest types of motion is unidirectional motion. Which of the following is the worst example of unidirectional motion? - Answers-C. The motion of ventilation heat as it travels from a furnace to various rooms in a home. The graph shows the motion of a theoretical particle in a particle accelerator. Which of the following statements is not correct? - Answers-C. The particle does not experience any instantaneous changes in position. The graph shows the motion of a theoretical particle in a particle accelerator. Which of the following statements is not correct? Graph - Answers-C. Downwards past the 1 x-axsis Look at the graph of the acceleration of a particle during various stages (A-E). Which of the following correctly describes a possible function for v during the given stage(s)? - Answers-B. In Stage A, the velocity function is −3t. Suppose a train travels in a straight line between two towns. During the course of the trip, the train stops, backs up a short distance, and eventually resumes moving forward toward the other town. Which of the following statements related to the displacement of the train is not correct? - Answers-D. The total distance traveled is equal to the distance between the two towns. In a demonstration a ball falls directly to the ground. Which of the following statements about this event is not correct? (Assume downward is the positive direction.) - Answers- A. The average velocity during the first half of the fall is greater than the average velocity during the entire experiment. Which of the following statements related to the two graphs is not correct? - Answers-C. The value for x at 3 seconds is not the same value for x at any other time. The Kleber family took a car trip one day that lasted 6 hours as shown on the graph. Which of the following statements about the Kleber's trip is correct? - Answers-A. During the first part of their trip, the average velocity was 50 km / h. Their average velocity between 4 and 6 hours was 75 km / h. Compare a ball and a sheet of paper falling. In the first example, the ball hits the ground before the sheet of paper. In the second example, the sheet of paper was crumpled into a ball shape, and the two objects hit the ground at the same time. Which of the following best explains this demonstration? - Answers-d. In the first example, the paper was subject to the forces of gravity as well as the significant force of air drag. In the second example, the force of air drag was minimized by decreasing the surface area of the paper. Which of the following statements about motion when there is constant acceleration is not correct? - Answers-a. x f=xi+viΔt−a(Δt)2 The plot shows velocity as a function of time. Assuming acceleration is constant and positive, which points correctly indicate vf, vi, and the average velocity? - Answers-b. vf=PointB; vi=Point A; v¯=Point D Air resistance can affect the falling motion of an object. Which of the following statements about air resistance is not correct? - Answers-d. All of the statements are correct. A squirrel sitting on a tree branch 17 m off the ground drops its acorn. Assume that the accorn has a constant acceleration of approximately 10 m / s2. How long will it take the acorn to hit the ground? - Answers-b. 1.8 s An object is observed for a 5 second interval. During this time, the object's velocity increases from 2 m / s to a final velocity and the object travels 75 m. The acceleration of the object is constant. Given this information, which of the following statements is not correct? - Answers-b. The final velocity of the object is 26 m / s. Suppose you throw an object straight up at an initial velocity of 17 m / s. How long will it take for the object to reach its maximum height? - Answers-n. 1.7s Which of the following is not one of the equations of kinematics with constant acceleration? - Answers-b. v2f=v2i+2aΔt You can manipulate the expression v¯¯¯=Δx/Δt to find one of the three master equations of kinematics. Which of the following is the master equation that gives an expression for xf? - Answers-D. : xf=xi+viΔt+(1/2)a(Δt)2 Which of the following does not show or describe constant acceleration? - Answers- graph - c. upwards The drawing shows the initial and final velocity vectors for a moving object, as well as Δv¯¯¯→Δ�¯→. What is the direction of the average acceleration vector, a¯¯¯→�¯→? - Answers-The correct answer is: Vector a¯¯¯�¯ points in the same direction as Δv¯¯¯→Δ�¯→. Suppose a train starts at point A and 35 seconds later, it reaches point B. What are the initial and final position vectors of the train? - Answers-The correct answer is: ri→=50mi^+100mj^rf→=225mi^−125mj^ The acceleration vector can be assessed in terms of a||�|| and a⊥�⊥. The parallel component is parallel to the direction of the velocity vector. Considering the velocity and acceleration vectors shown on the picture, which of the following statements is not correct? - Answers-The correct answer is: The object is slowing down and shifting in a counterclockwise direction. Which of the following expressions correctly relates v¯¯¯→�¯→, ΔtΔ�, and r→i - Answers-The correct answer is: r→f=r→i+v¯¯¯→Δt Which of the following is not a good example of uniform circular motion? - Answers-The correct answer is: a person taking off on an airplane to fly around the world on a path defined by the equator Which of the following is not correct? - Answers-The correct answer is: f = 2T = frequency: the number of revolutions around a circle per second. In a uniform circular motion, the average velocity is a¯¯¯=v2/r Which of the following statements about the derivation of this relationship is not correct. - Answers-The correct answer is: As Δt→0,Δ�→0, (Δr→/Δt)→a→, the instanteneous acceleration. A physicist on a train moving at 10 m / s observes a ball moving at 2 m / s in the same direction as the train's movement. Suppose someone standing still, to the side of the passing train, observes this event. A third person, in a car traveling at 5 m / s in the same direction as the train, also observes the event. Which of the following statements about the velocity of the ball is not correct? - Answers-d. All of these statements are correct. Relative motion is the motion of _____________. - Answers-The correct answer is: an object as described using two different reference frames or coordinate systems A jet is observed by two people. One person is standing in reference frame Q. A second person, in reference frame Q', that moves at a constant velocity, v→, to the right. At t=0, Q' is at the same location as Q. Which of the following statements about this event is not correct? - Answers-b. The position of the jet observed in reference frame Q′ equals the position of the jet observed in reference frame Q plus v. The compass of an airplane indicates that it is flying north at 450 mi/h. The wind velocity is 50 mi/h from the east to the west. The velocity of the airplane relative to the wind is v→A,W. The velocity of the airplane relative to the Earth is v→A,E. The velocity of the wind relative to the Earth is v→W,E. Which of the following statements is correct? - Answers-a. In the reference frame of the wind the plane's motion shifts toward the west. Which of the following is not an example of relative motion? - Answers-c. A plane is traveling at a speed of 500 mi / h. A daredevil is hanging onto one wing of the plane. The plane drops a package. The person flying the plane calculates the velocity of the package. The daredevil also calculates the velocity of the package. A boat is observed by a person standing on the opposite bank of a river. The boat crosses the river with a speed relative to the observer (v→B,O) of 15 m/s. The river has a constant downstream velocity (v→R,O) of 8 m/s. What is the magnitude of the velocity of the boat relative to the river (vB,R)? Also, find the value of θ. - Answers-The correct answer is: v→B,R=17m/s θ=28∘ The compass of an airplane indicates that it is flying south at 150 mi/h. There is a constant 40 mi/h wind blowing the airplane from west to east. The velocity of the airplane relative to the wind is v→A,W. The velocity of the airplane relative to the Earth is v→A,E. The velocity of the wind relative to the Earth is v→W,E. Given this information, what is the correct description for v→A,W? - Answers-The correct answer is: v→A,W= 155 mi/h in the SE direction A person weighing 600 N (mass = 60 kg) when at rest stands on a scale inside a train. The train begins to accelerate horizontally at a rate of 3.5 m / s2. What reading will the scale then give for the weight of the person? Use 10.0 m / s2 as the acceleration due to gravity on the Earth. - Answers-The correct answer is: 600 N An object with mass 5 kg is under a constant force (10i^+20j^) N. Its initial velocity is (−5i^+30j^) m/s. What will be its position 10 seconds later? - Answers-The correct answer is: (50i^+500j^) m Which of the following statements best describes the concept of uniform motion? - Answers-The correct answer is: In the absence of a net force, a moving body continues moving in a straight line with constant speed. An object with a mass of 5 kg is subject to a constant force. Its initial velocity is (−10i^+30j^) m/s. It is expected to be (20i^+10j^) after 10 seconds. What is the force? - Answers-The correct answer is: (15i^−10j^) N Suppose you carve out a small region exactly at the Earth's center and stand inside that region. What would you weigh? Assume the Earth is a perfect sphere and has a uniform density. - Answers-The correct answer is: 0 Which of the following best defines the variables in Newton's second law, F→=ma→? - Answers-The correct answer is: When an object is pushed or pulled, it is subject to a force; this is represented on the left side of the equation. The right side of the equation describes motion, in particular acceleration and kinematics (e.g., how velocity changes with time). The mass is the proportionality constant. Massive objects are sluggish and exhibit slower acceleration for given forces than less massive objects do. Overall, the right side describes motion and it indicates what happens when a force is applied to an object. Which of the following statements best describes an isolated body? - Answers-The correct answer is: An isolated body is neither pushed nor pulled by unbalanced forces and maintains a uniform, or steady, motion. Newton's third law is sometimes counterintuitive. For instance, it may be difficult to accept that when a car collides with a sport-utility vehicle (SUV), the small car pushes back with equal force on the large SUV. Given that Newton's third law is correct, which of the following is correct, and what does it suggest?Note: S = SUV, C = car - Answers- The correct answer is: Both A and B. The equations that state acceleration is proportional to force, a→αF→, and acceleration is inversely proportional to mass, a→α1/m, can be combined to form which of the following equations? - Answers-The correct answer is: a→=F→/m Newton's third law for any two objects, A and B, can be written as which of the following? - Answers-The correct answer is: F→AB=−F→BA The following answer choices describe a sequence of steps used by scientists when applying Newton's second law during experiments. Which of the following would not be used when applying Newton's second law? - Answers-The correct answer is: Choose a group of objects to observe. Diagrams A and B show a weight on an incline. Assume that the system has no friction. The x- and y-axes are also shown. Which of the following correctly states the simplest form of the equation needed to determine the acceleration? - Answers-The correct answer is: a→=g→sinθ Which of the following does not describe a quality of the ideal rope as an instrument of force? - Answers-The correct answer is: It has a consistent width. Look at the diagram showing an object on an incline. The weight of the object is represented by W−→ and the normal force by N→. The motion of the object in this diagram will occur in two dimensions, therefore, a coordinate system must be defined. Which of the following defines the optimal coordinate system for problems involving inclines? - Answers-The correct answer is: The x-axis should be parallel with the inclined surface, with the y-axis parallel to N→ The attached force diagram shows a weight hanging by a rope. The object is moving upward with a constant velocity. T→ equals the tension in the rope. The up arrow indicates the positive component of the vector. Which of the following equations related to this experiment is not correct? - Answers-The correct answer is: T + mg = Fnet The diagram shows a coffee filter falling to the ground. Given that F→net=0F→airdrag+W−→=0F→airdrag−mg→=0 Which of the following best describes the motion of the filter? - Answers-The correct answer is: The filter is moving downward at a constant velocity. Which of the following correctly describes force diagrams? - Answers-The correct answer is: Force diagrams allow you to calculate force, but not velocity. The diagram shows two carts attached by a string threaded through a frictionless pulley. Which of the following is the equation for the acceleration of the carts? - Answers-The correct answer is: a=M2/M1+M2---g