Your Name: _______________________ PHY203

Final Exam

12/14/07

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

Part 1

1-10 ________ (out of 50)

11 ________ (out of 50)

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

For problems 1-3, Let A = 6i - 5j, B = -7i + 10j, C = 3A – 2B

1. Write the vector, C, in vector notation:

a. 4i - 5j

b. 4i + 5j

c. 32i + 5j

d. 32i - 35j

e. None of the above

2. Find the magnitude of the vector B:

a. 3.0

b. 7.1

c. 12.2

d. 17.0

e. None of the above

3. Find the angle that vector A makes with the positive x-axis (measured in a

counterclockwise direction from the positive x-axis):

a. 40^o

b. 50^o

c. 310^o

d. 320^o

e. None of the above

4. A bike rider starts from rest with an acceleration of 0.066 m/s². Find how long it

takes the bike rider to ride 1.0 km:

a. 2.9 min.

b. 5.5 min.

c. 5.8 min.

d. 253 min.

e. None of the above

5. Consider two trains running in the same direction on parallel tracks. Train 1 passes the station at time, t = 0, with a constant speed of 5 m/s. Train 2 passes the station 30 seconds later than train 1 at a constant speed of 6 m/s. Find the time, t, at which the trains are exactly side-by-side:

a. 16.4 sec.

b. 150 sec.

c. 180 sec.

d. 210 sec.

e. None of the above

6. A police officer gives a burst of the car’s siren as the car is traveling towards a wall

at a speed of 100 m/s. The officer hears the siren sound reflected from the wall 1.0

sec. later. Find the distance the car was at the time the siren was sounded. (Use 343

m/s as the speed of sound in air):

a. 172 m

b. 221.5 m

c. 243 m

d. 343 m

e. None of the above

For problems 7-10, refer to the plot above:

7. Find the average speed from points C-G:

a. -8.3 m/s

b. -1.7 m/s

c. 1.7 m/s

d. 8.3 m/s

e. None of the above

8. Find the average velocity from points A-G:

a. -8.9 m/s

b. -2.2 m/s

c. 2.2 m/s

d. 8.9 m/s

e. None of the above

9. Find the instantaneous velocity at point D:

a. 0

b. -6.7 m/s

c. -5 m/s

d. -2.2 m/s

e. None of the above

10. Find the instantaneous acceleration at point F:

a. -6.67 m/s²

b. -5 m/s²

c. -2.22 m/s²

d. 0

e. None of the above

11. A boy who is standing on top of a 30m tall building throws a ball at a nearby building that is 100m tall. The initial velocity in the x-direction given to the ball is 30 m/s. When the ball lands on the roof of the second building it is traveling only in the horizontal direction. Show your work. (Note: use g = 9.81 m/s²).

a. Calculate the initial velocity of the ball in the y-direction.

b. Calculate the initial speed of the ball and the angle the ball made initially with respect to the horizontal (x-) direction.

c. Calculate the time it takes for the ball to reach the roof of the second building.

d. Write the velocity of the ball just as it is hitting the roof in vector notation using the coordinate system given above.

e. If the second building were not in the way, calculate how long it would take for the ball to hit the ground.

PHY203

Crib Sheet

Chapters 1-3

speed_AV = (total distance traveled)/Dt

Dx = x₂ – x₁ (displacement)

v_AV = Dx/Dt

a_AV = Dv/Dt

v_Inst = dx/dt

a_Inst = dv/dt

For constant acceleration:

x_f = x_o + v_ot + (1/2)at2

v_f = v_o + at

V_f2 = v_o2 + 2a(x_f - x_o)

g = 9.81 m/s2, the acceleration due to gravity (on Earth), unless otherwise directed

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

A_x = Acos(q)

A_y = Asin(q)

A = (A_x² + A_y²)^1/2

tan(q) = A_y/A_x

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