Exam 1--PHYS 201--Fall 2016

Transcription

1 Name: Exam 1--PHYS 201--Fall 2016 Multiple Choice-30 points Identify the choice that best completes the statement or answers the question 1 Which of these best approximates the area of a twin mattress (ie, just the area of the top part)? a 002 m 2 b 02 m 2 c 2 m 2 d 20 m 2 2 The mass of your desk is approximately a 1 kg b 10 kg c 100 kg d 1000 kg 3 How many significant figures should the solution to this expression have? a 4 b 3 c 2 d 1 e 0 4 Consider the following right triangle What is the angle, θ? a 40 b 50 c 20 d 80 5 The standard for the meter is based on which of the following? a the distance a silicon sphere will roll before stopping b the distance a cesium atom vibrates in a particular amount of time c the length of a bar in France d the distance light travels in a particular amount of time 6 The speed limit on some interstate highways is roughly 80 km/h What is this in meters per second? a 28 m/s b 62 m/s c 50 m/s d 22 m/s 7 You drive for 30 minutes at 30 mi/hr and then for another 30 minutes at 50 mi/hr What is your average speed for the whole trip? a more than 40 mi/hr b equal to 40 mi/hr c less than 40 mi/hr d not enough information 8 You drop a rock off a bridge When the rock has fallen 4 m, you drop a second rock As the two rocks continue to fall, what happens to their velocities? a the velocity of the second rock increases faster than the velocity of the first b both velocities stay constant c both increase at the same rate d the velocity of the first rock increases faster than the velocity of the second 1

2 9 You move along this track, measured in meters, from point A to point B What is your displacement? 12 Consider this graph Describe the motion of the object for these three time periods: A, B, and C a -3 m b -4 m c 4 m d -2 m e 3 m 10 You throw a ball upward with an initial speed of 10 m/s Assuming that there is no air resistance, what is its speed when it returns to you? a less than 10 m/s b equal to 10 m/s c more than 10 m/s 11 Consider this position versus time graph Which of the following best represents the velocity versus time graph for the object described in the position versus time graph? a A: the object is travelling at a constant speed B: the object has a negative acceleration C: the object is increasing position at a constant rate b A: the object is not moving B: the object has an increasing speed in the positive direction C: the object is travelling at a constant, positive speed c A: the object has a constant, non-zero velocity B: the object has an increasing position C: the object has an increasing speed d A: the object is in the same position B: the object has a positive acceleration C: the object has an increasing speed a a b b c c d d 2

3 Problem--70 points total Please show all work 13 (15 pts) Consider this graph of position versus time The function for the motion is given on the plot a) What is the average velocity between t=1 and 5 seconds? b) Graphically find the instantaneous velocity at t=4 seconds Show how you do this on the plot c) What is the function for the velocity? The acceleration? d) Calculate the velocity at t=4 s e) Sketch the velocity versus time graph for this motion Do not attempt to represent the actual values for the velocities; only show the correct shape of the plot and represent the appropriate signs for the velocity 3

4 14 (10 pts) Show whether these equations are dimensionally correct If correct, circle Yes I v= ax Yes or No II x=at 2 + vt Yes or No 15 (10 pts) Derive the equations of motion Begin with the differential definitions for acceleration (a=dv/dt) and velocity (v=dx/dt) III x=2vt 3x v2 ax Yes or No 4

5 16 (10 pts) Consider the following graph of velocity versus time a) What is the average acceleration of the runner between t=2 and 8 seconds? b) What distance does the runner travel between 0 and 12 seconds? c) Draw the position versus time graph that represents this motion 5

6 17 (15 pts) You throw a ball upwards It travels to a height of 20 m before turning around and returning to your hand a) How long does it take to travel to the top of the trajectory? b) What is the ball s initial speed? c) What is the position of the ball at t=3 seconds? d) What is the velocity of the ball at t=2 seconds? 18 (10 pts)in a slap shot, a hockey player accelerates the puck from a velocity of 500 m/s to 3000 m/s in the same direction If this shot takes s, calculate the distance over which the puck accelerates 6

7 ID: A Exam 1--PHYS 201--Fall 2016 Answer Section MULTIPLE CHOICE 1 ANS: C REF: F16 2 ANS: B REF: F16 3 ANS: B REF: F16 4 ANS: A REF: F16 5 ANS: D REF: F16 6 ANS: D REF: F16 7 ANS: B REF: F16 8 ANS: C REF: F16 9 ANS: B REF: F16 10 ANS: B REF: F16 11 ANS: C REF: F16 12 ANS: B REF: F16 PROBLEM 13 ANS: 14 ANS: Y,Y,Y 15 ANS: 16 ANS: 17 ANS: 18 ANS: 0350 m 1