T‐1
A
car
accelerates
from
zero
to
30
m/s
in
10
seconds.
Its
acceleration
is
m/s²
T‐1
A
car
accelerates
from
zero
to
30
m/s
in
10
seconds.
Its
acceleration
is
a
=
v/t
=
(30
m/s)/(10
s)
=
3
m/s²
3m/s²
A‐1
A
truck
travels
500
meters
in
20
seconds.
What
is
its
average
speed?
m/s
A‐1
A
truck
travels
500
meters
in
20
seconds.
What
is
its
average
speed?
v
=
d/t
=
500
m
/
20s
=
25m/s
25m/s
A‐2
An
object
of
mass
1
kg
traveling
at
10
m/s
hits
an
object
of
mass
2
kg
initially
at
rest.
If
the
first
object
comes
to
rest
how
fast
does
the
second
object
move?
m/s
A‐2
An
object
of
mass
1
kg
traveling
at
10
m/s
hits
an
object
of
mass
2
kg
initially
at
rest.
If
the
first
object
comes
to
rest
how
fast
does
the
second
object
move?
m_1*v_1
=
m_2*v_2
1
kg*10
m/s
=
2
kg
*
v_2v_2=5
m/s
5m/s
A‐3
A
1
kg
mass
is
suspended
from
the
ceiling
by
a
massless
spring
with
the
force
constant
of
20
N/m.
How
much
will
the
spring
stretch
when
the
mass
is
at
rest?
(Use
g=10
m/s²
for
the
free‐fall
acceleration.)
m
A‐3
A
1
kg
mass
is
suspended
from
the
ceiling
by
a
massless
spring
with
the
force
constant
of
20
N/m.
How
much
will
the
spring
stretch
when
the
mass
is
at
rest?
(Use
g=10
m/s²
for
the
free‐fall
acceleration.)
20
N/m
*
x
=
1
kg
*
10
m/s²

x=0.5
m
0.5m
A‐4
An
object
with
mass
10
kg
is
accelerated
from
rest
to
a
speed
2
m/s
in
a
distance
2
m
by
a
constant
force
F.
What
is
the
magnitude
of
F?
N
A‐4
An
object
with
mass
10
kg
is
accelerated
from
rest
to
a
speed
2
m/s
in
a
distance
2
m
by
a
constant
force
F.
What
is
the
magnitude
of
F?
Work:
W=F*distance=F*2m
Kinetic
Energy:
K=0.5*10kg*(2m/s)²
W=K

F=10
N
10N
B‐1
A
20
kg
wagon
is
pulled
with
a
60
N
force
that
is
parallel
to
the
ground.
What
is
the
acceleration
of
the
wagon?
m/s²
B‐1
A
20
kg
wagon
is
pulled
with
a
60
N
force
that
is
parallel
to
the
ground.
What
is
the
acceleration
of
the
wagon?
60
N
=
20
kg
*
a

a
=2
m/s²
3m/s²
B‐2
A
block
with
mass
of
1
kg
moving
at
a
speed
of
6
m/s
collides
and
sticks
to
a
2
kg
block
that
is
initially
at
rest.
What
is
the
speed
of
the
two
blocks
after
the
collision?
m/s
B‐2
A
block
with
mass
of
1
kg
moving
at
a
speed
of
6
m/s
collides
and
sticks
to
a
2
kg
block
that
is
initially
at
rest.
What
is
the
speed
of
the
two
blocks
after
the
collision?
m_1*v_1
=
(m_1+m_2)*v
1
kg
*
6
m/s
=(1
kg
+2
kg)*v
v=2
m/s
2m/s
B‐3
A
car
of
mass
1200
kg
is
parked
on
a
hill
inclined
at
angle
30
degrees
from
the
horizontal.
What
is
the
force
of
static
friction
on
the
car?
(Use
g=10
m/s²
for
the
free‐fall
acceleration.)
N
B‐3
A
car
of
mass
1200
kg
is
parked
on
a
hill
inclined
at
angle
30
degrees
from
the
horizontal.
What
is
the
force
of
static
friction
on
the
car?
(Use
g=10
m/s²
for
the
free‐fall
acceleration.)
Friction
cancels
gravity
component
along
plane:
m
g
sin(30º)
=
1200
*
10
*
0.5
=
6000
6000N
B‐4
If
300
g
of
water
at
80
ºC
is
mixed
with
100
g
of
water
at
40
ºC,
the
mixture
will
have
temperature
ºC
B‐4
If
300
g
of
water
at
80
ºC
is
mixed
with
100
g
of
water
at
40
ºC,
the
mixture
will
have
temperature
Heat
flow
=
mcDT.
Total
inward
flow=0
100g*c*(T‐40ºC)
+
300g*c*(T‐80ºC)
T=70ºC
70ºC
C‐1
The
brakes
are
applied
to
a
car
traveling
at
20
m/s,
and
it
accelerates
at
‐5
m/s².
The
time
required
to
stop
is
s
C‐1
The
brakes
are
applied
to
a
car
traveling
at
20
m/s,
and
it
accelerates
at
‐5
m/s².
The
time
required
to
stop
is
V_0+
a
T
=0
20
m/s+(‐5
m/s²)
T=0T=4
s
4s
C‐2
A
meter
stick
has
a
mass
of
200
g.
A
small
300
g
mass
is
attached
at
the
70
cm
mark.
At
which
mark
is
the
center
of
mass?
cm
C‐2
A
meter
stick
has
a
mass
of
200
g.
A
small
300
g
mass
is
attached
at
the
70
cm
mark.
At
which
mark
is
the
center
of
mass?
(200
g*
50
cm+300
g
*
70
cm)/(200g
+300
g)
=
62
cm
62cm
C‐3
A
ball
is
dropped
from
a
height
of
1.8
m
onto
a
hard
surface.
What
is
the
speed
of
the
ball
when
it
hits
the
surface?
(Use
g=10
m/s²
for
the
free‐fall
acceleration.)
m/s
C‐3
A
ball
is
dropped
from
a
height
of
1.8
m
onto
a
hard
surface.
What
is
the
speed
of
the
ball
when
it
hits
the
surface?
(Use
g=10
m/s²
for
the
free‐fall
acceleration.)
Potential
energy
is
converted
to
kinetic
energy:
mgh=(1/2)
m
v²
v²=g*h*2=10*1.8*2=366m/s
6
m/s
C‐4
A
ball
is
thrown
at
a
vertical
wall
30
meters
away,
with
a
velocity
30
m/s
at
an
angle
of
45º.
At
what
height
above
the
starting
point
will
it
strike
the
wall?
(Use
g=10
m/s²
for
the
free‐fall
acceleration.)
m
C‐4
A
ball
is
thrown
at
a
vertical
wall
30
meters
away,
with
a
velocity
30
m/s
at
an
angle
of
45º.
At
what
height
above
the
starting
point
will
it
strike
the
wall?
(Use
g=10
m/s²
for
the
free‐fall
acceleration.)
vx
=
30
m/s
*
cos
45
=15
sqrt[2]

t
=
x/vx
=
sqrt[2]
s
h
=
vy
*
t
‐gt²/2
=
30
–
10
=
20
20m
D‐1
What
is
the
acceleration
of
a
particle
if
mass
of
the
particle
is
4
kg
and
force
applied
on
it
is
24
N?
m/s²
D‐1
What
is
the
acceleration
of
a
particle
if
mass
of
the
particle
is
4
kg
and
force
applied
on
it
is
24
N?
F=maa
=F/m=24/4=6
6m/s²
D‐2
How
much
energy
is
required
to
raise
the
temperature
of
100
g
of
water
from
20
ºC
to
50
ºC?
(The
specific
heat
of
water
is
1
cal/gºC.)
cal
D‐2
How
much
energy
is
required
to
raise
the
temperature
of
100
g
of
water
from
20
ºC
to
50
ºC?
(The
specific
heat
of
water
is
1
cal/gºC.)
energy
=(50º
‐
20º)
*
100
g
*
1
cal/gºC
=
3000
calories
3000cal
D‐3
An
automobile
has
two
headlamps
with
a
resistance
of
2
ohms
each,
connected
in
parallel.
They
are
connected
across
an
18
volt
battery.
What
is
the
current
drawn
from
the
battery?
amps
D‐3
An
automobile
has
two
headlamps
with
a
resistance
of
2
ohms
each,
connected
in
parallel.
They
are
connected
across
an
18
volt
battery.
What
is
the
current
drawn
from
the
battery?
1/Rtot=1/R+1/R=2/RV
=
IRtot
=IR/2
I
=
2V/R
=
2*18v
/
2
ohms
=
18
amp
18amps
D‐4
A
200
lb
astronaut
goes
to
a
planet
whose
mass
is
3
times
that
of
the
earth,
and
whose
radius
is
twice
that
of
earth.
What
is
his
weight
on
that
planet?
lb
D‐4
A
200
lb
astronaut
goes
to
a
planet
whose
mass
is
3
times
that
of
the
earth,
and
whose
radius
is
twice
that
of
earth.
What
is
his
weight
on
that
planet?
F(earth)
=
GMm/r²
=
200
lb
F(planet)
=
G(3M)m/(2r)²
=
¾(GMm/r²)
=
(3/4)
F(earth)
150lb
S‐1
A
rocket
is
fired
straight
up
with
a
velocity
100
m/s.
How
long
will
it
take
to
return
to
the
launcher?
(The
acceleration
of
gravity
on
the
earth
is
g=10
m/s²)
s
S‐1
A
rocket
is
fired
straight
up
with
a
velocity
100
m/s.
How
long
will
it
take
to
return
to
the
launcher?
(The
acceleration
of
gravity
on
the
earth
is
g=10
m/s²)
100‐gt=
‐100

t=(200m/s)
/(10
m/s²)=20s
20s
S‐2
Masses
of
3
kg
and
2
kg
are
connected
by
a
massless
string
which
passes
over
a
massless
and
frictionless
pulley.
When
the
masses
are
released,
what
is
the
magnitude
of
the
acceleration
of
the
5
kilogram
mass?
(Use
g=10
m/s²
for
the
free‐fall
acceleration.)
m/s²
S‐2
Masses
of
3
kg
and
2
kg
are
connected
by
a
massless
string
which
passes
over
a
massless
and
frictionless
pulley.
When
the
masses
are
released,
what
is
the
magnitude
of
the
acceleration
of
the
5
kilogram
mass?
(Use
g=10
m/s²
for
the
free‐fall
acceleration.)
F=
(3
kg
+
2
kg)
*
a,
F
=
(3
kg
‐
2
kg)
*
10
m/s²

a
=
2
m/s²
2
m/s²
S‐3
A
stone
thrown
from
the
top
of
a
building
with
a
speed
20
m/s
straight
upward.
The
building
is
25
m
high,
and
the
stone
just
misses
the
edge
of
the
roof.
Find
the
speed
of
the
stone
when
it
hits
the
ground.
(Use
g=10
m/s²
for
the
free‐fall
acceleration)
m/s
S‐3
A
stone
thrown
from
the
top
of
a
building
with
a
speed
20
m/s
straight
upward.
The
building
is
25
m
high,
and
the
stone
just
misses
the
edge
of
the
roof.
Find
the
speed
of
the
stone
when
it
hits
the
ground.
(Use
g=10
m/s²
for
the
free‐fall
acceleration)
By
energy
conservation,
0.5
M
(20
m/s)^2
+
M
(10
m/s²)
(25
m)
=
0.5
M
v²

v²
=900
(m/s)²
v=30
m/s
30m/s
S‐4
A
planet
has
the
same
density
as
Earth
and
7
times
the
Earth's
radius.
What
is
the
acceleration
of
gravity
on
the
planet?
(The
acceleration
of
gravity
on
the
earth
is
g=10
m/s²)
m/s²
S‐4
A
planet
has
the
same
density
as
Earth
and
7
times
the
Earth's
radius.
What
is
the
acceleration
of
gravity
on
the
planet?
(The
acceleration
of
gravity
on
the
earth
is
g=10
m/s²)
g
=G
M/R²
g_2/g_1
=
(M_2/M_1)*
(R_1/R_2)²
M_i
=
(4
pi/3)
rho
(R_i)²
R_i

g_2
=
g
(R_2/R_1)
=
10
m/s²
*
7
2
70m/s