PHY
105
(Grobe)
Final
Exam
Review
Questions
and
answers
A
car
drives
around
a
circle
with
a
constant
speed
of
55m/sec.
What
is
its
average
velocity
after
one
round?
-
ANSWER-0
mph
because
the
speed
is
only
constant;
it
does
not
change
We
know
a=V/t.
How
does
it
depend
on
V
and
a?
-
ANSWER-t
=
V/a
You
add
a
vector
pointing
north
to
another
vector
pointing
south.
Is
it
possible
that
the
sum
vector
is
zero?
-
ANSWER-yes,
if
both
vectors
have
the
same
length
A
runner
runs
with
a
constant
velocity
of
17
m/sec
for
7
seconds.
What
is
her
average
acceleration?
-
ANSWER-0
m/s^2
because
acceleration
requires
a
change
in
velocity
A
large
tank
holds
400
kiloliter
of
water.
How
many
liters
of
water
is
this?
-
ANSWER-4x10^5
liters
A
car
is
driving
along
a
straight
line
with
a
const.
speed
of
10m/sec.
What
is
its
instantaneous
acceleration?
-
ANSWER-0
m/s^2
A
ball
rolls
off
a
platform
that
is
50
m
above
the
ground
with
an
initial
horizontal
velocity
of
10
m/sec.
What
is
the
amount
of
the
vertical
distance
the
ball
has
fallen
after
2
sec?
-
ANSWER-20
m
A
car
drives
3
m/sec.
How
long
does
it
take
to
drive
3
miles?
-
ANSWER-1610
-
Solve
by
taking
the
miles
given
and
converting
it
to
the
desired
units
Five
identical
resistors,
each
R
=2
Ω,
are
connected
in
series
to
a
battery
of
10
V.
What
is
the
current
through
each
resistor?
-
ANSWER-1A
You
have
to
find
total
resistance
from
the
5
resistors.
So
2x5=
10Ω
total.
>>
**diff
from
parallel**
We
know
that
I(total)=
V/R
so...
10V/10
Ω=
1A
for
each
resistor A
mass
20
kg
is
pulled
and
changes
its
velocity
from
23
m/sec
to
33
m/sec
in
5
seconds.
What
is
the
force?
-
ANSWER-40
N
33-32=
[(10)/2]*20=
40N
A
100-kg
man
in
an
elevator
is
accelerating
up
at
2
m/sec2?
What
is
the
total
force
acting
on
him?
-
ANSWER-200N
USE:
Ftot
=
ma
m=
100
kg
a=
2
m/s^2
(use
acceleration
given)
A
45.5
kg
woman
in
an
elevator
is
accelerating
up
at
2.8
m/s2?
What
is
her
weight?
-
ANSWER-455
N
USE:
Fgrav
=
ma
m=
45.5
kg
a=
10
m/s^2
(Use
the
accel
consatnt
for
gravity)
Two
forces
of
13
N
each
act
in
the
same
direction
and
a
third
force
of
3
N
acts
in
the
opposite
direction
on
a
box.
The
box
accelerates
with
2
m/sec2.
What
is
the
mass
of
the
box?
-
ANSWER-1 1.5
kg
Add
up
the
forces
in
the
same
direction,
subtract
3N
(opposing
force),
then
divide
by
2
A
74-kg
woman
in
an
elevator
is
accelerating
down
at
10
m/sec2?
What
is
the
force
on
her
due
to
the
elevator?
-
ANSWER-0
Because
the
elevator
is
MOVING
DOWN
A
ball
is
thrown
up.
What
is
the
amount
of
the
acceleration
at
the
highest
point
of
motion?
-
ANSWER-10
m/sec2
Four
cars
of
mass
10
kg
each
are
connected
by
a
rod.
The
right
most
car
is
pulled
to
the
right
with
a
force
of
40N.
What
is
the
acceleration
of
the
left
most
car?
-
ANSWER-1
m/s2
A
45
kg
woman
in
an
elevator
is
accelerating
down
at
3
m/s2?
What
is
the
amount
of
the
net
force
acting
on
her?
-
ANSWER-135
N 45*3=135N
When
a
skydiver
reaches
her
terminal
velocity
(due
to
friction),
what
is
her
acceleration?
-
ANSWER-0
because
she
has
stopped
speeding
up
once
she
hit
terminal
velocity,
therefore
she
does
not
experience
acceleration
A
book
of
mass
3
kg
rests
on
a
table?
What
is
the
amount
of
the
total
force
acting
on
it?
-
ANSWER-0
Because
Ftot
must
=
0
When
something
is
at
rest
(ie
an
objecting
resting
on
something
else)
forces
cancel
out
Is
it
true
that
the
order
in
which
the
three
vectors
A,
B,
C
are
summed
up
is
irrelevant?
In
other
words,
is
A+B+C
the
same
vector
as
B
+
C
+A?
Which
statement
is
correct?
-
ANSWER-A
+
B
+
C
is
the
same
as
B+
C
+A
When
a
skydiver
reaches
her
terminal
velocity
(due
to
friction),
what
the
total
force
acting
on
her?
-
ANSWER-0
N
A
65
kg
man
in
an
elevator
is
accelerating
up
at
4
m/s2?
What
is
his
weight?
-
ANSWER-650
N
USE:
Fgrav=
(10m/s^2)*(mass)
A
68-kg
woman
in
an
elevator
is
accelerating
down
at
1
m/sec2?
What
is
her
weight?
-
ANSWER-680
N
USE:
Fgrav=
(10m/s^2)*(mass)
When
a
skydiver
of
mass
50
kg
reaches
her
terminal
velocity
(due
to
friction),
what
is
her
weight?
-
ANSWER-500
N
One
string
pulls
an
object
at
an
angle
of
500.
A
second
string
(with
a
different
force)
pulls
the
same
object
at
an
angle
of
900.
Is
it
possible
that
the
object
starts
to
move
in
a
direction
of
550?
-
ANSWER-yes,
it
is
possible
105
(Grobe)
Final
Exam
Review
Questions
and
answers
A
car
drives
around
a
circle
with
a
constant
speed
of
55m/sec.
What
is
its
average
velocity
after
one
round?
-
ANSWER-0
mph
because
the
speed
is
only
constant;
it
does
not
change
We
know
a=V/t.
How
does
it
depend
on
V
and
a?
-
ANSWER-t
=
V/a
You
add
a
vector
pointing
north
to
another
vector
pointing
south.
Is
it
possible
that
the
sum
vector
is
zero?
-
ANSWER-yes,
if
both
vectors
have
the
same
length
A
runner
runs
with
a
constant
velocity
of
17
m/sec
for
7
seconds.
What
is
her
average
acceleration?
-
ANSWER-0
m/s^2
because
acceleration
requires
a
change
in
velocity
A
large
tank
holds
400
kiloliter
of
water.
How
many
liters
of
water
is
this?
-
ANSWER-4x10^5
liters
A
car
is
driving
along
a
straight
line
with
a
const.
speed
of
10m/sec.
What
is
its
instantaneous
acceleration?
-
ANSWER-0
m/s^2
A
ball
rolls
off
a
platform
that
is
50
m
above
the
ground
with
an
initial
horizontal
velocity
of
10
m/sec.
What
is
the
amount
of
the
vertical
distance
the
ball
has
fallen
after
2
sec?
-
ANSWER-20
m
A
car
drives
3
m/sec.
How
long
does
it
take
to
drive
3
miles?
-
ANSWER-1610
-
Solve
by
taking
the
miles
given
and
converting
it
to
the
desired
units
Five
identical
resistors,
each
R
=2
Ω,
are
connected
in
series
to
a
battery
of
10
V.
What
is
the
current
through
each
resistor?
-
ANSWER-1A
You
have
to
find
total
resistance
from
the
5
resistors.
So
2x5=
10Ω
total.
>>
**diff
from
parallel**
We
know
that
I(total)=
V/R
so...
10V/10
Ω=
1A
for
each
resistor A
mass
20
kg
is
pulled
and
changes
its
velocity
from
23
m/sec
to
33
m/sec
in
5
seconds.
What
is
the
force?
-
ANSWER-40
N
33-32=
[(10)/2]*20=
40N
A
100-kg
man
in
an
elevator
is
accelerating
up
at
2
m/sec2?
What
is
the
total
force
acting
on
him?
-
ANSWER-200N
USE:
Ftot
=
ma
m=
100
kg
a=
2
m/s^2
(use
acceleration
given)
A
45.5
kg
woman
in
an
elevator
is
accelerating
up
at
2.8
m/s2?
What
is
her
weight?
-
ANSWER-455
N
USE:
Fgrav
=
ma
m=
45.5
kg
a=
10
m/s^2
(Use
the
accel
consatnt
for
gravity)
Two
forces
of
13
N
each
act
in
the
same
direction
and
a
third
force
of
3
N
acts
in
the
opposite
direction
on
a
box.
The
box
accelerates
with
2
m/sec2.
What
is
the
mass
of
the
box?
-
ANSWER-1 1.5
kg
Add
up
the
forces
in
the
same
direction,
subtract
3N
(opposing
force),
then
divide
by
2
A
74-kg
woman
in
an
elevator
is
accelerating
down
at
10
m/sec2?
What
is
the
force
on
her
due
to
the
elevator?
-
ANSWER-0
Because
the
elevator
is
MOVING
DOWN
A
ball
is
thrown
up.
What
is
the
amount
of
the
acceleration
at
the
highest
point
of
motion?
-
ANSWER-10
m/sec2
Four
cars
of
mass
10
kg
each
are
connected
by
a
rod.
The
right
most
car
is
pulled
to
the
right
with
a
force
of
40N.
What
is
the
acceleration
of
the
left
most
car?
-
ANSWER-1
m/s2
A
45
kg
woman
in
an
elevator
is
accelerating
down
at
3
m/s2?
What
is
the
amount
of
the
net
force
acting
on
her?
-
ANSWER-135
N 45*3=135N
When
a
skydiver
reaches
her
terminal
velocity
(due
to
friction),
what
is
her
acceleration?
-
ANSWER-0
because
she
has
stopped
speeding
up
once
she
hit
terminal
velocity,
therefore
she
does
not
experience
acceleration
A
book
of
mass
3
kg
rests
on
a
table?
What
is
the
amount
of
the
total
force
acting
on
it?
-
ANSWER-0
Because
Ftot
must
=
0
When
something
is
at
rest
(ie
an
objecting
resting
on
something
else)
forces
cancel
out
Is
it
true
that
the
order
in
which
the
three
vectors
A,
B,
C
are
summed
up
is
irrelevant?
In
other
words,
is
A+B+C
the
same
vector
as
B
+
C
+A?
Which
statement
is
correct?
-
ANSWER-A
+
B
+
C
is
the
same
as
B+
C
+A
When
a
skydiver
reaches
her
terminal
velocity
(due
to
friction),
what
the
total
force
acting
on
her?
-
ANSWER-0
N
A
65
kg
man
in
an
elevator
is
accelerating
up
at
4
m/s2?
What
is
his
weight?
-
ANSWER-650
N
USE:
Fgrav=
(10m/s^2)*(mass)
A
68-kg
woman
in
an
elevator
is
accelerating
down
at
1
m/sec2?
What
is
her
weight?
-
ANSWER-680
N
USE:
Fgrav=
(10m/s^2)*(mass)
When
a
skydiver
of
mass
50
kg
reaches
her
terminal
velocity
(due
to
friction),
what
is
her
weight?
-
ANSWER-500
N
One
string
pulls
an
object
at
an
angle
of
500.
A
second
string
(with
a
different
force)
pulls
the
same
object
at
an
angle
of
900.
Is
it
possible
that
the
object
starts
to
move
in
a
direction
of
550?
-
ANSWER-yes,
it
is
possible
