Physics I Exam 1 Fall 2014 (version A)

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1 Physics I Exam 1 Fall 014 (version A) Section Number Section instructor Last/First Name (print) / Last 3 Digits of Student ID Number: Answer all questions, beginning each new question in the space provided. Show all work. Show all formulas used for each problem prior to substitution of numbers. Label diagrams and include appropriate units for your answers. Write your name and section number at the top of each page in the space provided and write the name of your section instructor in the place provided in the cover sheet.you may use an alphanumeric calculator (one which exhibits physical formulas) during the exam as long as you do not program any formulas into memory. By using an alphanumeric calculator you agree to allow us to check its memory during the exam. Simple scientific calculators are always appropriate! A Formula Sheet Is Attached To The Back Of This Examination For your convenience you may carefully remove it from the Exam. Please take it with you at the end of the exam or throw it in a waste basket. Be Prepared to Show your Student ID Card Score on each problem: I. (5) II. (5) III. (5) IV. (5) Total Score (out of 100 pts)

2 Last Name only (print) Section Number Part I. (5 points each) Put a circle around the letter that you think is the best answer. I-1 The figure shows the graph of the position x as a function of time for an object moving in the straight line (the x-axis). Which of the following graphs best describes the velocity along the x-axis as a function of time for this object? A) B) C) D) E) I- As shown in the figure, three force vectors act on an object. The magnitudes of the forces as shown in the figure are = 80.0 N, = 60.0 N, and = 40.0 N, where N is the standard SI unit of force. The resultant force acting on the object is given by A) 180 N at an angle 60.0 with respect to +x-axis. B) 60.0 N at an angle 90.0 with respect to +x-axis. C) 0.0 N at an angle 34.3 with respect to +x-axis. D) 35.5 N at an angle 34.3 with respect to +x-axis. E) 40.0 N at an angle 60.0 with respect to +x-axis.

3 3 I-3 What is the magnitude of + +, where = , = and = ? A) 7.07 B).00 C) D) 6.78 E) 8.1 I-4 Which one of the following free-body diagrams best represents the free-body diagram, with correct relative force magnitudes, of a person in an elevator that is traveling upward but is gradually slowing down at a rate of 9 m/s? f is the force of the floor on the person and g is the force of gravity on the person. A) B) C) D) E) I-5 A ball is tied to the end of a cable of negligible mass. The ball is spun in a circle with a radius.00 m making 7.00 revolutions every 10.0 seconds. What is the magnitude of the acceleration of the ball? A) 67.9 m/s B) 38.7 m/s C) 9.3 m/s D) 14.8 m/s E) 74. m/s

4 Last Name only (print) Section Number 4 Part II (5 points each part total of 5 points) A car starts from rest at a stop sign. It accelerates at 4.0 m/s for 6.0 s, moves at constant velocity for.0 s, and then slows down at a rate of 3.0 m/s, coming to rest at the next stop sign. A) Draw and label a motion diagram for the car. B) Determine the distance traveled by the car in the first time interval. C) Determine the distance traveled by the car in the second time interval. D) Determine the distance traveled by the car in the third time interval. E) Determine the number of seconds for the third time interval.

5 Last Name only (print) Section Number 5 Part III (5 points each part total of 5 points) A particle s motion (acceleration, velocity, displacement) is described by the following equations: at ( ) = 1t 18 vt ( ) = 6t 18t xt t t 3 ( ) = Assume that standard S.I. units are used. A) Determine the displacement during the time interval from 1 to seconds. B) Determine the average velocity during the time interval from 1 to seconds. C) Determine the instantaneous velocity at 1.5 seconds. D) Determine the time (it any) that the velocity is zero. E) Determine the average acceleration during the time interval from 1 to seconds.

6 Last Name only (print) Section Number 6 Part IV (5 points each part total of 5 points) A projectile is shot from the edge of a cliff 115 m above ground level with an initial speed of 65.0 m/s at an angle of 35 degrees above the horizontal. It takes 9.96 seconds to hit the ground. A) Draw and label a diagram of the physical situation. B) Determine the horizontal distance the the projectile goes while in the air. C) Determine the horizontal and vertical components of the velocity as it hits the ground. D) Determine the direction of the projectile as it hits the ground. E) Determine the maximum height (above ground) that the projectile reaches.

7 Formulae for Exam #1 Fall 014 (side 1) 7 Graphical Analysis r vavg = t t = t t a v a avg inst inst f v = t dr = i dv = = r = r r (slope of position versus time) f i (slope of velocity versus time) (slope of position versus time at a specific time) d r (slope of velocity versus time at a specific time) S f = S i + area under velocity versus time for Δt = t f - t i V fs = V is + area under acceleration versus time for Δt = t f - t i Analytical Analysis (for constant linear acceleration) S 1 f = Si + vis + t as t vfs = vis + as t v = v + a S fs is S ( )

8 8 Graphical Analysis Formulae for Exam #1 Fall 014 (side ) ω a avg avg θ = t (slope of angular position versus time) ω = t (slope of angular velocity versus time) dθ ω inst = (slope of angular position versus time at a specific time) dω α inst = = d θ (slope of angular velocity versus time at a specific time) Ɵ f = Ɵ i + area under angular velocity versus time for Δt = t f - t i ω fs = ω is + area under angular acceleration versus time for Δt = t f - t i Analytical Analysis (for constant angular acceleration) θ 1 f = θi + ωi + t α t ωf = ωi + α t ω = ω + α θ s f i ( ) = rθ v= rω at = ra a r r = ω = v r

Physics I Exam 2 Spring 2015 (version A)

Physics I Exam 2 Spring 2015 (version A) 95.141 Physics I Exam Spring 015 (version A) Section Number Section instructor Last/First Name (PRINT) / Last 3 Digits of Student ID Number: Answer all questions, beginning each new question in the space