Your Name:  _______________________                              PHY203

                                                                                                            Exam #1

                                    Chapters 1-3

                                                                                                            Thurs, 10/0109

 

 

 

Lecture Time:         9 a.m             1p.m.             2p.m.       3p.m.       Honors         

 

 

 

1-10    _________________        (out of 50)

 

 

 

11       _________________        (out of 20)

 

 

 

12       _________________        (out of 30)

 

 

 

Total              _______________

 

 

 

Multiple choice answer sheet-shade in correct answers below

(one choice per problem):

 

 

 

1

 

2

 

3

 

4

 

5

 

6

 

7

 

8

 

9

 

10

 

a

 

 

 

 

 

 

 

 

 

 

 

b

 

 

 

 

 

 

 

 

 

 

 

c

 

 

 

 

 

 

 

 

 

 

 

d

 

 

 

 

 

 

 

 

 

 

 

e

 

 

 

 

 

 

 

 

 

 

 

 

PHY203

Exam #1

Crib Sheet

Chapters 1-3

 

 

speedAV = (total distance traveled)/Dt

 

Dr = r2 – r1 (displacement)

vAV = Dr/Dt

 

aAV = Dv/Dt

 

vInst = dr/dt

 

aInst = dv/dt

 

 

For constant acceleration:

xf = xo + vot + (1/2)at2

 

vf = vo + at

 

Vf2 = vo2 + 2a(xf - xo)

 

use g = 9.81 m/s2, the acceleration due to gravity, unless otherwise directed

 

For a vector A with magnitude A and direction q (measured counterclockwise with respect to the x-axis):

Ax = Acos(q)

Ay = Asin(q)

A = (Ax2 + Ay2)1/2

tan(q) = Ay/Ax

 

quadratic eq. sol.:      If ax2 + bx + c = 0; then x = -b+(b2-4ac)1/2/(2a)

 

1. A runner runs a marathon (26.2 miles) in 4 hours. What is the average speed in m/s?

a.      2.9 x10-3 m/s

b.     1.13 x10-3 m/s

c.      1.13 m/s

d.      2.9 m/s

e.      None of the above

 

2.   Add 0.66 kiloliters to 15,000 milliliters:

a.      81 l

b.     6.75x102 l

c.      8.1x102 l

d.      6.6x103 l

e.      None of the above

 

For problems 3 and 4 consider two trains traveling in the same direction on parallel tracks. The measurements start when the fronts of the trains are 500m apart. In all cases below, train 1 is traveling to the right and passes the position x=0 at t=0 traveling in the positive x-direction at a constant speed of 5 m/s. In all cases below, find the x position at which the front of train 2 is side-by-side to the front of train 1:

3. Case 1: Train 2 passes the x= -500m position at t=0 traveling with a constant speed of 3 m/s.

a.           192 m

b.          308 m

c.           833 m

d.          1333 m

e.          None of the above

 

4. Case 2: Train 2 passes the x= -500m position at t=0 traveling with a constant speed of 8 m/s.

a.           192 m

b.          308 m

c.           833 m

d.          1333 m

e.          None of the above

 

For problems 5 and 6, a runner runs 1.5 km in the positive x direction, then turns around and runs 1.0 km back in the direction of the starting point. The total time of the run is 15 min.

5. Find the total distance and total displacement of the run.

a.           -500m, 2500m

b.          2500m, -1000m

c.           500m, 2500m

d.          2500m, -500m

e.          2500m, 500m

 

6. Find the average speed and average velocity distance of the run.

a.           -0.56m/s, 2.78m/s

b.          2.78m/s, -0.56m/s 

c.           0.56m/s, 2.78m/s,  

d.          2.78m/s, 0.56m/s   

e.          None of the above

 

For problems 7-10, on Planet XXX where the acceleration due to gravity is exactly 10m/s2, a soccer ball is kicked from ground level and misses the goal, just clearing the top of the net at the ball's highest point.  The height of the top of the net is 1.5 m and the ball is kicked from a distance of 4 m from the net.

 

7.  Calculate the y-component of the initial velocity.

a.           3.9 m/s                    

b.          5.48 m/s                  

c.           15 m/s

d.          30 m/s

e.          None of the above

 

8.  Calculate the time it takes for the ball to just reach the goal.                             

a.           0.39 sec.                 

b.          0.55 sec                  

c.           1.5 sec.

d.          3.0 sec.

e.          None of the above

 

9.  Calculate the x-component of the initial velocity.

a.           1.33 m/s                  

b.          2.7 m/s                    

c.           7.3 m/s

d.          10.2 m/s

e.          None of the above

 

10.  Calculate the magnitude of the velocity as the ball just crosses the top of the

net.

a.           1.33 m/s                  

b.          2.7 m/s                    

c.           7.3 m/s

d.          10.2 m/s

e.          None of the above

 

 

                                    s

11.  Let           A = 5i + 3j, B = 4i - 7j, C = -6j

 

a.  Sketch and clearly label the vectors A , B , and C on the above graph.

 

Show your work.

b.  For the vector A, find the magnitude of the vector and the angle the vector

makes with respect to the x-axis (measured from the positive x-axis in a

counterclockwise direction).

 

 

 

 

 

c.  For the vector B, find the magnitude of the vector and the angle the vector

makes with respect to the x-axis (measured from the positive x-axis in a

counterclockwise direction).

 

 

 

 

 

d.  Write the vector, D= A-4B+3C, in vector notation.

 

 

 

 

12. 2 balls are dropped or thrown from a cliff. Rock a is thrown straight up at t=0 with an initial speed of 20 m/s; rock b is dropped from the cliff at t=3 sec. (Use g=9.81m/s2) Show your work.

a.  Using the coordinate system given in the figure, write the equation of motion for rock a.

 

 

 

b.  Using the coordinate system given in the figure, write the equation of motion for rock b.

 

 

 

 

c.  Find the time at which the rocks are side-by-side.

 

 

 

 

 

 

 

d.  Find the height below the cliff at which the rocks are side-by-side.

 

 

 

 

e. If the height of the cliff is 500m, find the distance that rock b travels in the last second before hitting the ground. 

 

 

 

 

 

 

Extras

 

2. A swimmer swims a 5000m race in 1000s. What was the speed in miles per hour?

a.      5.05x10-3 cm3

b.     1.98x102 cm3

c.      2.84x103 cm3

d.      5.05x103 cm3

e.      None of the above

 

 

For problems 8-11 consider two trains traveling in the same direction on parallel tracks. The measurements start when they are 500m apart. In all cases below, train 1 is traveling to the right and passes the position x=0 at t=0 traveling in the positive x-direction at a constant speed of 5 m/s. In all cases below, find the x position at which train 2 is parallel to train 1:

10. Case 3: Train 2 starts from rest at the x=-500m position at t=0s traveling with a constant magnitude of acceleration of 4 m/s2.

a.          85.6 m

b.          66m

c.           77.6m

d.          132m

e.          None of the above

 

11. Case 3: Train 2 starts from rest at the x=-500m position at t=5s traveling with a constant magnitude of acceleration of 4 m/s2.

a.           55m

b.          66m

c.           77.6m

d.          132m

e.          None of the above

 

For problems 12-15, Let  A = 6j, B = 3i - 4j,   C = -3i - 5j, and D = 3A + 4B – 6k

 

12.  Find the magnitude of the vector A and the angle that vector A makes with

the positive x-axis (measured in a counterclockwise direction from the positive x-

axis):

a.        6,        90o

b.        5.0,     0o

c.         2.23,   90o

d.         5.0,     90o

e.         None of the above

 

13.  Find the magnitude of the vector B and the angle that vector B makes with

the positive x-axis (measured in a counterclockwise direction from the positive x-

axis):

a.        5,        301o

b.        3.3,     320.2o

c.         7.8,     309.8o

d.         7.8,     320.2o

e.         None of the above

 

14.  Find the magnitude of the vector C and the angle that vector C makes with

the positive x-axis (measured in a counterclockwise direction from the positive x-

axis):

a.        5.8,     246.6o

b.        3.6,     236.3o

c.         3.6,     303.7o

d.         3.6,     326.3o

e.         5.0,     326.3o

 

15.  Find the magnitude of the vector D:

a.         13.6

b.        38.7

c.         41.4

d.         42.9

e.         None of the above

 

16.  On Planet XXX where the acceleration due to gravity is exactly 10m/s2, consider a ball dropped from a cliff with a height of 200m. Find the distance the ball travels in he last second before hitting the ground:

a.          58.5 m

b.          125m

c.           150m

d.          175m

e.          None of the above (never catches up)

 

17.  On Planet XXX where the acceleration due to gravity is exactly 10m/s2, consider a ball thrown straight up with an initial speed of 5 m/s from a cliff. Find the distance below the cliff the ball will be located after 10 sec.:

a.          450 m

b.          125m

c.           150m

d.          175m

e.          None of the above (never catches up)

 

7.  Case 3: rock a is dropped from the cliff at t=0 sec.; rock b is thrown straight up at t=5 sec. with an initial speed of 5 m/s.

a.          3 sec.

b.          125m

c.           150m

d.          175m

e.          None of the above (never catches up)