Download Let gEarth= 10 m/s2 throughout the exam

Let gEarth= 10 m/s2 throughout the exam
I.
You push on a 20 kg lawn mower that is in motion to the right, exerting a 100 N
force on it that is directed 30° below the horizontal. There is a frictional force acting
to the left, and the effective coefficient of kinetic friction between the grass and
mower is 0.60.
a) Draw a force diagram (to scale) for the lawn mower on the graph paper at right. Be
sure to label forces.
b) How much does the ground push up on the lawn mower?
c) Find the acceleration of the lawn mower.
d) While you are pushing the lawn mower it moves (circle one)
to the right
to the left
and it is (circle one)
speeding up
Explain your choices:
slowing down
moving with a constant velocity
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Let gEarth= 10 m/s2 throughout the exam
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II. A ball of mass Mball traveling at a speed of vball swings at the end of a string. The
string passes through a hollow tube and is attached at the other end to a hanging block.
The slanted part of the string that swings in a circle makes an angle with the horizontal
of θ, as shown. Assume that the hanging mass is at rest and stays at rest.
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Assume these are given quantities: Mball , vball ,θ
a) Draw one force diagram for the ball, and one for the hanging block. Be sure to
label all forces.
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c) Find the mass of the hanging block in terms of the given quantities and any constants.
d) If the mass of the ball is 200g, and it travels at a speed of 2.28 m/s, and the string makes an angle of 37°
with the horizontal:
i. how massive is the hanging block?
ii. how big is the radius of the circular path?
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b) Apply Newton’s 2nd law to the ball, and then do the same for the block to get three DIFFERENT
equations for the tension in terms of the given quantities, the radius and/or any other physical constants.
Let gEarth= 10 m/s2 throughout the exam
3. A cart with wheels is placed on a horizontal table. A string tied to the
cart passes over a pulley and is attached to a hanging weight as shown
at right. The string pulls on the cart with a constant force, and friction
and air resistance can be ignored. If the cart is released from rest,
which choice below best describes its motion?
4.
a)
The cart moves with a constant speed.
b)
The cart quickly speeds up until it reaches a steady speed that depends on the
size of the weight.
c)
The cart remains at rest unless the hanging weight is greater than the weight of
the cart.
d)
The cart is always speeding up until it hits the pulley.
e)
The cart speeds up and then slows down as the hanging mass gets closer to the
ground.
The masses in the figure hang across a massless, frictionless
pulley. What is the tension in the rope?
a) 0.5 mg
T
b) mg
c) 1.33 mg
d) 2 mg
m
2m
e) 1.5 mg
5.
Which of the following will remain in the air the MOST amount of time (neglecting air
resistance)?
a)
A marble launched straight up from the ground at 18 m/s
b)
A marble launched from the ground with a speed of 20 m/s at an angle of 60°
from the horizontal
c)
A marble that stays in the air for 3.0 s
d)
A marble that is dropped from 50 m above the ground
e)
A marble that is launched horizontally from a 50 m high
TIPERS
Let g
= 10 m/s2 throughout the exam
Earth
B3.WWT98: ASTnONAUT
NEAR n PUnET AND a Moon GnAVFATIoNAL Fonce
At the instant shown, Catalina, an astronaut, is in space a
planet Barolo.
2d from
theCatalina,
A moon of
6. Atdistance
the instant
show,
an astronaut,
is Barolo,
in space a
Aquitania,
is a distance
d onBorolo.
the otherA
side
of Barolo.
A
distance
2d from
the planet
moon
of Borolo,
physics student trying to calculate the gravitational force on
Aquitania, states:
is a distance d on the other side of Barolo. At
Catalina
the moment shown, Catalina’s acceleration is:
―
―
―
Catalina
―
―
翼
〔
"We onb need to worry about the planet Barolo, not its
moon. !
Since
! Catalina is on the other side of Barolo, the
! !! ! !!
gravitational
field due to Aquitania is blocked by Barolo. The
a)
! ! acting on Catalina is the gravitational force due to
only force
Barolo,
!!!whichwe canfind using Newton's law of universal gravitation."
b)
Barolo
Aquitania
―
―
―
…
…
…
…
…
…
0-
3計
L 2
!! !
What, if anythitg, is wrong with the student's statement? If nothing is wrong, state that explicitly, and then
!
! !!why
!!! it is correct.
explain
c)
If the statement
is incorrect, state what is wrong and how you would correct
it.
!!
d) You need to know what kind of motion Catalina is in to determine her acceleration.
e) You need to know Catalina’s mass to determine her acceleration.
7. A 1-kg block and a 4-kg block are pushed across a table as shown. The blocks are
speeding up. Which of the following statements is true about
the amount of force exerted on the 4-kg block by the 1-kg
block as compared to the force exerted on the 1-kg block by
the 4-kg block?
B3.CT99: ASTnONAUT NEAR A MOON-GRAvITATIoNAL Fonce
is smaller.
Ina)bothItcases
shown at right, an astronaut is a distance x from a
moon. The two cases are identical except that in Case A there is
b) It is greater.
large planet directly between the astronaut and the moon.
1 kg
a
case
A
!
4 kg
Planet
two forces
areon
equal.
gravitational
Isc)the The
force
the astronaut by the moon (i)
(iii)acceleration
(ii)
greater
greater
in
A,
Case
in Cas€ B,oforthe
the same in in order to answer this.
d) We need to know the direction
both cases?
―
e)
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We need to know how hard the hand pushes in order to answer IElttllχ
this.
Explain your reasoning.
Case B
8. The moon orbits the earth (RE=6380 km) every 27.3 days. The mean
distance between
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8
the center if the earth and the center the moon is 3.84 x 10 m. Which of the following is
closest to the period of a satellite that is 800 km above the earth’s surface?
「
a)
1.6 hours
b)
1.8 days
c)
1.4 hours
d)
1.7 hours
e)
10.6 hours
Copyright @ 2Ol5 Pearson Education, Inc.
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