PHYSICS HW FOR NANCY ONLY!!1

for NANCY ONLY!!!

1

NAME__________________

EXAM 1

Directions: Answer the following questions on the attached sheets of paper. Please adhere

to the following guidelines to reduce any suspicions of cheating:

1. KEEP YOUR EYES ON YOUR OWN EXAM AT ALL TIMES.
2. KEEP YOUR ANSWERS COVERED AT ALL TIMES.
3. Do not communicate with any other student during the exam.
4. Do not use any unauthorized prepared material during the exam.
5. Only acceptable calculators may be used on the exams.
6. Do not leave the room at any time before handing in your exam.
7. SHOW ALL OF YOUR WORK (answers may not be accepted without work

shown)

EQUATIONS

if
xxx 

t

x

v

x






dt

dx
v

x


t

v
a

x
x







dt

dv
a

x
x


tavv
xxx



0

2

00
2

1
tatvxx

xx
 )(2

0
2
0

2
xxavv

xxx


tvvxx
xx
)(

2

1
00

 tavv





0

2

00
2

1
tatvr

r





g

v
h

2

sin
0

22

0



g

v
R 0

2

0
2sin 



jAiA

A

yx

ˆˆ 


22

yx
AAA 

















x

y

A

A
1

tan

cosABBA 


sinABBA 


r
v
a

c

2


dt

vd
a

t


 raaa rt ˆ
ˆ  



v

r
T

2


amF


 nf
kk

 nf
ss



Earth: mR

E

6
1038.6  , kgm

E

24
1097.5 

2

1. A stone is thrown straight up with a speed of 25.0 m/s from the top of a building 55.0 m

tall.

a. How far above the ground will the stone go?

b. How long until the stone hits the ground?

c. What is the speed of the stone just before it hits the ground?

d. If a ball is thrown downward from the top of the same building with a speed of

25.0 m/s, will its speed just before hitting the ground be greater than, less than, or

equal to the speed of the stone just before it hits the ground? Explain. (Hint:

What is the speed of the stone when it returns to the height it was thrown?)

3

2. A ball is thrown from the top of a building of height 40m at an angle of 20˚ above the
horizontal and with an initial speed of 15m/s. Use the assumptions of projectile motion

to answer the following questions.

a. How high above the ground will the ball travel?
b. What speed will the ball have at the maximum height?
c. What is the direction of the velocity of the ball at the maximum height?
d. How far has the ball traveled horizontally when it hits the ground?
e. What will be the speed of the ball when it hits the ground?

4

3. Consider the frictionless system below. The pulley is massless and frictionless, and the
string is massless. The mass of each block is ma = 2.0 kg, mb = 1.0 kg, mc = 2.0 kg, and

md = 1.0 kg.

a. What is the acceleration of the system?
b. What is the tension in the string between block a and block b?
c. What is the tension in the string between block b and block c?
d. What is the tension in the string between block c and block d?
e. If the system is initially at rest, how long will it take block d to fall 3.0 m?

5

4. Two equal masses of 20kg are attached by a massless string and are sliding down an

inclined plane of 35˚. The coefficients of kinetic friction between the blocks and the

ramp are different. The top block has coefficient 700.0
1


k
 and the bottom block has

coefficient 500.0
2


k
 . The system accelerates down the plane and the string remains

tight.

a. Draw a free body diagram for each block.
b. Calculate the tension in the string.
c. Find the magnitude of the acceleration of the blocks.

6

5. A train slows down as it rounds a sharp horizontal turn, slowing from 25.0 m/s to 13.9
m/s in 15.0 s. The radius of the curve is 150 m.

a. Calculate the magnitude of the tangential component of the acceleration (assumed
constant).

b. Calculate the magnitude of the radial component of the acceleration (when the
train reaches 13.9 m/s).

c. Calculate the magnitude of the total acceleration (when the train reaches 13.9
m/s).

d. Calculate the angle of the total acceleration vector relative to the radial
component (when the train reaches 13.9 m/s).