Download Fall Semester Review - Physics [Regular]

Name:________________________
Period:___
Fall Semester Review – Regular Physics 2012
USE YOUR FORMULA CHART!!!!!!!!!!!!
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
_D___
1.
If some measurements agree closely with each other but differ widely from the actual value, these measurements are
a. neither precise nor accurate.
b. accurate but not precise.
c. acceptable as a new standard of accuracy.
d. precise but not accurate.
__C__
2.
These values were obtained as the mass of a bar of metal: 8.83 g; 8.84 g; 8.82 g. The known mass is 10.68 g. The values are
a. accurate.
b. both accurate and precise.
c. precise.
d. neither accurate nor precise.
__A__
3.
An object is described to have 0.0 m/s at rest. Which of these terms does that describe?
a. zero speed
c. zero acceleration
b. free fall acceleration
d. zero net force
____
7.
Position (meters)
Relationship of position versus time
__C___ 4. What does the graph above illustrate about velocity and acceleration?
a. The velocity is positive: the acceleration is positive.
b. The velocity is constant: the acceleration is constant.
c. The velocity is positive: the acceleration is zero.
d. There is not enough information to answer.
2
1.5
1
0.5
0
0
0.5
1
1.5
2
Time (seconds)
__C__
__A__
__D__
___A__ 5. Which of the following statements best describes the motion of this object.
a. The object is moving at a constant velocity.
b. The object is changing direction.
c. The object is speeding up.
d. The object is slowing down.
6. The time rate changing velocity is known as what?
a. velocity
c. acceleration
7.
The slope of a position versus time graph represents ?
a. Velocity
c. Acceleration
b. force
d. displacement
b.
d.
force
Displacement
8. Find the time it takes for a car with initial velocity of 10 m/s, to acceleration to 5 m/s2 and reach a speed of 25 m/s?
a. 0 s
b. 2 s
c. 1 s
d. 3 s
Diagram: (Given + Unknowns)
Equation: a = (vf – vi) / t
Horizontal
a = 5 m/s2
vf = 25 m/s
vi = 10 m/s
t = ???? s
Δd = ??? m
Substitute:
/
t = (vf – vi)
a
t = (25 – 10)
5
Solve:
__D__
9.
t =3s
What is the displacement of a car that moves from x = +5.0 m to x = -10.0 m in 3 seconds? (a = 0)
a. +10 meters
b. -5 meters
c. -5 meters
d. -15 meters
= 15
5
=3s
____
10.
__A____ 10. What does the graph above illustrate about
acceleration?
a. The acceleration varies.
b. The acceleration is zero.
c. The acceleration is constant.
d. The acceleration increases then becomes constant.
__C__
11.
A curious kitten pushes a ball of yarn with its nose. It displaces the ball of yarn, from rest, a displacement of 17.5 cm in 2.00 s. What is
the acceleration of the ball of yarn?
a. 0.11 m/s2
b. 0.144 m/s2
2
c. 0.0875 m/s
d. 0.0438 m/s2
Diagram: (Given + Unknowns)
Equation: Δd = (vi)t + (1/2) a (t)2
Horizontal
Substitute:
2
a = ????? m/s
vf = ????? m/s
vi = 0 m/s
t =2s
Δd = 17.5 cm = 0.175 m
0.175 = (0 m/s)(2s) + (1/2)(a) (2 s)2
0.175 =
0
+ 2a
0.175 =
2a
0.0875 m/s2 = a
Solve:
__D__
12. A race car accelerates from 5.0 m/s to 35.0 m/s with an acceleration 3 m/s2. What is the vehicle's displacement?
a. 10 m
b. 150 m
c.
87.5 m
d.
200 m
Diagram: (Given + Unknowns)
Equation: a = (vf2 – vi2) / 2Δd
Horizontal
a = 3 m/s2
vi = 5 m/s
vf = 35 m/s
t = ??? s
Δd = ???? m
Substitute:
a = (vf2 – vi2)
2Δd
Δd = 1200
6
Δd = (vf2 – vi2)
2a
Δd = (352 – 52)
2(3)
= 200 m
Solve:
__C__
0.0875 m/s2 = a
Δd = 200 m
13.
A car traveling at 3 m/s accelerates uniformly for 6.0 s in order to pass a snow plow. The car travels 108 m during the 6.0 s
interval that it was accelerating. What is the car’s speed at the end of the acceleration period.
a. 27 m/s
b. 30 m/s
c. 33 m/s
d. 42 m/s
Diagram: (Given + Unknowns)
Equation: Δd = (vi)t + (1/2) a (t)2
a = (vf – vi) / t
Horizontal
a = ????? m/s2
vf = ????? m/s
vi = 3 m/s
t = 6.0 s
Δd = 108 m
Substitute:
108 = (3 m/s)(6s) + (1/2)(a) (6 s)2
108 =
18
+ 18a
90 =
18a
5 m/s2 = a
a = (vf – vi)
t
5 = (vf – 3)
6
30 = (vf – 3)
33 m/s = vf
Solve:
vf = 33 m/s
__D__
_B___
14.
The value 9.8 m/s2 would represent which of the following
a. free fall velocity
b.
c. free fall acceleration
d.
acceleration due to gravity
Both B and C
15.
A 0.180 kg arrow is shot vertically straight up with an initial velocity of 12 m/s. What is the maximum height it will go?
a. 5.98 m
b. 7.34 m
c. 11.96 m
d. 21.94 m
Diagram: (Given + Unknowns)
Equation:
a = (vf2 – vi2) / 2Δd
Vertical
Substitute:
a = -9.8 m/s2
vf = 0 m/s
vi = 12 m/s
t = ???? s
Δd = ???? m
a = (vf2 – vi2)
2Δd
∆ dy = -144/-19.6
∆ dy = 7.34 m
Δd = (vf2 – vi2)
2a
Δd = (02 – 122)
2(-9.8)
Solve:
__B__
∆ dy = 7.34 m
16.
A 0.180 kg arrow is shot vertically straight up with an initial velocity of 12 m/s. How long does it take to reach it maximum height?
a. 0.81 s
b. 1.22 s
c. 2.16 s
d. 3.22 s
Diagram: (Given + Unknowns)
Equation:
a = (vf – vi) / t
Substitute:
Vertical
a = -9.8 m/s
vf = 0 m/s
vi = 12 m/s
t = ???? s
Δd = ???? m
2
t = (vf – vi)
a
/
t = (0 – 12)
-9.8
= -12
-9.8
= 1.22 s
t = 1.22 s
Solve:
t = 1.22 s
_C___
17.
After winning the Super Bowl, Aaron Rodgers throws his helmet vertically upward and catches it in the same spot as returns to his hand.
At the top of its path, the helmet is experiencing
a. nonzero velocity and nonzero acceleration
b. nonzero velocity and zero acceleration
c. zero velocity and nonzero acceleration
d. zero velocity and zero acceleration
__A__
18.
When there is no air resistance, objects of different masses fall _____________.
a. with equal accelerations
b. with different accelerations
c. according to mass
d. sideways
__B___
19. A boy on a wagon travels 6.0 m west and 8.0 m south. The magnitude of the resultant (vector sum ) of the displacement would be?
a. 0 m
b. 10 m
c. 12 m
d. 14 m
Diagram: (Given + Unknowns)
Equation: a2 + b2 = c2
Horizontal
Δdx = 6.0 m
Vertical
Δdy = 8.0 m
Can’t directly add horizontal with vertical.
Substitute:
(6 m)2 + (8 m)2 = c2
36
+ 64
= c2
2
100 = c
10 m = c
Solve:
__C__
20.
Which of the following is a physical quantity that has a magnitude but no direction?
a. Vector
b. resultant
c. Scalar
d. frame of reference
_A___
21.
Which of the following is a physical quantity that has both magnitude and direction?
a. Vector
b. resultant
c. Scalar
d. frame of reference
Δdnet = 10 m
__A__
22.
A lightning bug flies at a velocity of 0.25 m/s due east toward another lightning bug seen off in the distance. A light easterly breeze
blows on the bug at a velocity of 0.25 m/s. What is the resultant velocity of the lightning bug?
a. 0.50 m/s east
b. 0.75 m/s east
c. 0.00 m/s east
d. 0.25 m/s east
_D___
23.
A quarterback takes the ball from the line of scrimmage and runs backward for 10 m then sideways parallel to the line of scrimmage for
15 m. The ball is thrown forward 50 m perpendicular to the line of scrimmage. The receiver is tackled immediately. What is the total
distance that ball traveled?
a. 0 m
b. 50 m
c.
25 m
d. 75 m
_B___
24.
What is the trajectory of a projectile?
a. a wavy line
b. a parabola
c. a hyperbola
d. projectiles do not follow a predictable path.
__D_____ 25. A lead cylinder is dropped from a cliff. How far did it fall in 3.0 s?
a.
9.8 m
b. 29.4 m
c.
14.7 m
d. 44.1 m
Diagram: (Given + Unknowns)
Equation:
Vertical
Vertical
a = - 9.8 m/s2
vf = ???? m/s
vi = 0 m/s
t = 3.0 s
Δdy = ????? m
Substitute
∆ dy = vi t
∆dy = (0 m/s)(3.0s)
∆dy =
0
∆dy = - 44.1 m
Solve:
_C___
(1/2)at2
(1/2)(-9.8)(3.0)2
- 44.1
+
+
+
∆dy = - 44.1 m (answer choice should be negative)
26.
A 70.0 kg lead projectile is shot horizontally at 40 m/sec from the top of a 50 m high tower. How far from the base of the
tower does it hit the ground?
a. 3.19 m
b. 86.4 m
c. 127.6 m
d. 200.0 m
Diagram: (Given + Unknowns)
Equation: Vertical: ∆ dy = vi t +(1/2)at2
Horizontal ∆ dx =vi t+(1/2)at2
Horizontal
a = 0 m/s2
vf = 40 m/s
vi = 40 m/s
t = ??? s
Δdx = ????? m
Vertical
a = - 9.8 m/s2
vf = ??? m/s
vi = 0 m/s
t = ???? s
Δdy = 50 m
Mass is not needed for this problem.
Ultimately, looking for Δdx = ???? m
_B___
∆ dy = vi t + (1/2)at2
Substitute: (Vertical)
(Horizontal)
∆ dx =vi t+(1/2)at2
∆ dx = (40)(3.19)+(1/2)(0)(3.19)2
∆ dx = 127.6
+ 0
∆ dx = 127.6 m
∆ dy = vi t
+
(1/2)at2
50 m = (0 )(t) + (1/2)(-9.8)(t)2
50 m =
0
+ -4.9 t2
2
50 m = -4.9t
-10.2 = t2
3.19 s = t
Solve:
∆ dx = 127.6 m
27.
A stone is thrown horizontally from the top edge of a cliff with an initial speed of 12 m/s. A stopwatch measures the stone’s trajectory
time from the top of the cliff to the bottom at 5.6 s. What is the height of the cliff? (Disregard air resistance. )
a. 58 m
c. 120 m
b. 154 m
d. 180 m
Diagram: (Given + Unknowns)
Equation: Vertical
∆ dy = vi t + (1/2)at2
Horizontal
a = 0 m/s2
vf = 12 m/s
vi = 12 m/s
t = 5.6 s
Δdx = ????? m
Vertical
a = - 9.8 m/s2
vf = ??? m/s
vi = 0 m/s
t = 5.6 s
Δdy = ???? m
Substitute:
∆ dy = vi t
∆dy = (0 m/s)(5.6s)
∆dy =
0
∆dy = -154 m
+
+
+
(1/2)at2
(1/2)(-9.8)(5.6)2
-154
Looking for Δdy = ???? m
Solve:
∆dy = 154 m (height is scalar, must be positive)
__B__
__A__
28.
29.
Which of the following is the cause of an acceleration?
a. Speed
c. Inertia
b.
d.
Force
Velocity
What is the correct name for speeding up, slowing down, or changing direction?
a. Acceleration
b. Inertia
c. Velocity
d. Force
____
_____
31.
31.
___D__ 30. In the free-body diagram shown, which of the following is the gravitational force
acting on the car?
a. 775 N
b. 5800 N
c. 13,690 N
d. 14,700 N
___B__ 31. In the free-body diagram shown, what is the net force in the x –direction?
a. 1,010 N
b. 5,025 N (left)
c. 6,575 N
d. 20,390 N
__A___ 32. In the free body diagram shown, what is the net for in the y-direction?
a. 1,010 N (down)
b. 5,025 N
c. 6,575 N
d. 20,390 N
__A__
A go-cart with a weight of 500 N is accelerated across a flat surface at 0.7 m/s 2. How much net force acts on the go-cart?
a. 36 N
b. 73 N
c. 350 N
d. 714 N
Diagram: (Given + Unknowns)
Equation:
(Vertical)
Fg= ma
(Horizontal)
Fa = ma
33.
(Horizontal)
Fa = ???? N
m = ??? kg
a = 0.7 m/s2
(Vertical)
Fg = 500 N
m = ???? kg
a = 9.8 m/s2
Substitute:
(Vertical)
Fg= ma
(Horizontal)
Fa = ma
500 N = m (9.8 m/s2)
m = (500 N)/ (9.8m/s2)
m = 51.0 kg
------------------------------------------------------------F = (51.0 kg)(0.7m/s2)
Fa= 35.7 N
Solve:
__C__
34.
Which of the following is the tendency of an object to maintain its state of motion?
a. Acceleration
b. Force
c. Inertia
d. Velocity
__B__
35.
If a nonzero net force is acting on an object, then the object is definitely _________.
a. at rest
b. Accelerating
c. moving with a constant velocity
d. losing mass
__C__
36.
A wagon with a weight of 300.0 N is accelerated across a level surface at 0.5 m/s2. What net force acts on the wagon?
a. 9.0 N
b. 150 N
c. 15 N
d. 610 N
Diagram: (Given + Unknowns)
Equation: (vertical)
Fg= ma
(horizontal)
Fa = ma
(Horizontal)
Fa = ???? N
m = ??? kg
a = 0.5 m/s2
(Vertical)
Fg = 300 N
m = ???? kg
a = 9.8 m/s2
Substitute:
(Vertical)
Fg= ma
300 N = m (9.8m/s2)
m = (300 N)/ (9.8m/s2)
m = 30.58 kg
(Horizontal) ----------------------------------------------------------------Fa = ma
F = (30.58 kg)(0.5m/s2)
Fa= 15.29 N
Solve:
_B___
Fa= 35.7 N (closest to 36 N)
37.
Fa= 15.29 N (closest to 15 N)
According to Newton’s second law, F=ma, when the same force is applied to two objects of different masses,
a. the object with greater mass will experience a great acceleration and the object with less mass will
experience an even greater acceleration.
b. the object with greater mass will experience a smaller acceleration and the object with less mass will
experience a greater acceleration.
c. the object with greater mass will experience a greater acceleration and the object with less mass will
experience a smaller acceleration.
d. the object with greater mass will experience a small acceleration and the object with less mass will
experience an even smaller acceleration.
_D___
38.
According to Newton’s 1st Law of motion, a moving object acted on by a net force of zero, __________.
a. Remains at rest
b. increases its inertia
c. Decelerates at a constant rate
d. move at a constant rate
__A__
39.
A hockey stick hits a puck on the ice. Identify an action-reaction pair.
a. The stick exerts a force on the puck; the puck exerts a force on the stick.
b. The stick exerts a force on the puck; the puck exerts a force on the ice.
c. The puck exerts a force on the stick; the stick exerts a force on the ice.
d. The stick exerts a force on the ice; the ice exerts a force on the puck.
_B___
40.
The statement by Newton that for every action there is an equal but opposite reaction is which of his laws of motion?
a. first
b. third
c. second
d. fourth
_B___
__D__
__C__
41. What is the net force on the object pictured to the right ?
a. 5 N to the left
b. 10 N the right
c. 35 N to the right
d. 60 N to the right
25 N
20 N
0.5 kg
15 N
42. What is the net acceleration on this object pictured to the right ?
a. 0 m/s2
b. 5 m/s2 the right
c. 10 m/s2 to the right
d. 20 m/s2 to the right
43.
The magnitude of the force of gravity acting on an object is called?
a. frictional force
b. inertia
c. weight
d. mass
__A__
44.
A sled weighing 1.0 x 102 N sits on level ground. What is the normal force of the slope acting on the sled? (Draw a FBD!!!!!)
a. 100 N
b. 0.098 N
c. 10 N
d. 9.8 N
__B__
45.
There are six books in a stack, and each book weighs 5 N. A constant force of 2.0 N causes the stack to move with constant velocity.
What is the frictional force acting on the books?
a. 30 N
b. 2 N
c. 5 N
d. 32 N
__C__
46.
The moon revolves around the earth once every year. Which object experiences a great gravitational force?
a. the moon
b. the earth
c. they are the same
d. not enough information to tell
__C__
47.
A set of physics textbooks weighs 294 N on earth, what would they weigh on a planet that has ½ the mass and ½ the radius of earth?
a. 147 N
b. 294 N
c. 588 N
d. 1176 N
_D___
48.
After a cannon ball is fired into frictionless space, the amount of force needed to keep it moving equals ____.
a. twice the force with which is was fire
b. the same amount of force with which it was fired
c. one half the force with which it was fired
d. zero, since no force is necessary to keep it moving
_E___
49.
Equilibrium occurs when ____.
a. all the forces acting on an object are balanced
b. the sum of the force acting right equal the sum of the forces acting left
c. the sum of the force acting up equal the sum of the forces acting down
d. the net force is zero
e. all of the above
__B__
50.
A force does work on an object if the force _________.
a. is perpendicular to the displacement of the object
b. is parallel to the displacement of the object
c. perpendicular to the displacement of the object moves the object along a path that returns the object to its
starting position
__D__
51.
Which of the following energy forms is the sum of kinetic energy and all forms of potential energy?
a. total energy
b. summative energy
c. non mechanical energy
d. mechanical energy
___B_
52.
The
a.
b.
c.
d.
more powerful the motor is, the __________.
longer the time interval for doing the work is
shorter the time interval for doing the work is
greater the ability to do the work is
shorter the workload is
_B___
53.
A horizontal force of 200 N is applied to move a 55 kg television set across a 10 m level surface. What is the work done by the 200 N
force on the television set?
a. 4000 J
b. 2000 J
c. 5000 J
d. 6000 J
Diagram: (Given + Unknowns)
Equation: W = f(d)
F = 200 N
m = 55 kg
d = 10 m
W = ???? J
Substitute:
W = 200 N (10 m)
W = 2000 J
Mass is not needed for this
problem.
Solve:
_C___
54.
Which of the following energy forms is involved as a pencil falls from a desk?
a. kinetic energy only
b. non-mechanical energy
c. gravitational potential energy and kinetic energy
d. elastic potential energy and kinetic energy
239 kg
PE =mgh
4.0 m
at 4 m
PEi = 9,369 J
KEi = 0 J
1 m at 1m
PE = 2,342 J
KE = 7,026 J
__A__
55. What is the kinetic energy of the barrel as it sits on the top shelf?
a. 0 J
b. 2,342 J
c. 7,026 J
d. 9,369 J
__D__
56. What is the potential energy of the barrel as it sits on the top shelf?
a. 0 J
b. 2,342 J
c. 7,026 J
d. 9,369 J
__D__
57. What is the mechanical energy of the barrel as it sits on the top shelf?
a. 0 J
b. 2,342 J
c. 7,026 J
d. 9,369 J
__D__
58. When the barrel falls, what is the kinetic energy right before it hits the ground?
a. 0 J
b. 2,342 J
c. 7,026 J
d. 9,369 J
_7026 J___ 60. What is the kinetic energy of the falling barrel if the height is 1.0 m above the ground?
a. 0 J
b. 2,342 J
c. 7,026 J
d. 9,369 J
_7.7 m/s___
KE = 1/2mv2
62.
Use the following scenario for the following questions.
The picture to the right shows a 239 kg barrel of toxic waste sitting on the ledge of 4.0 m high shelf.
__2342 J__ 59. What is the potential energy of the falling barrel if the height is 1.0 m above the ground?
a. 0 J
b. 2,342 J
c. 7,026 J
d. 9,369 J
at 0 m
PEf = 0 J
KEf = 9,369 J
__D__
W = 2000 J
61. What is the velocity of the falling barrel if the height is 1.0 m above the ground?
a. 0 m/s
b. 4.0 m/s
c. 7.7 m/s
d. 8.9 m/s
A 3.00 kg toy falls from a height of 10.0 m. Just before it hits the ground, what is its kinetic energy?
a. 98.0 J
c. 0.98 J
Diagram: (Given + Unknowns)
m = 3.00 kg
g =9.8 m/s2
h = 10 m
b.
d.
Equation:
Substitute:
top PE = mgh
KE = 0 J
bottom PE = 0 J
KE = ½ mv2
29.4 J
294 J
KEi + PEi = KEf + PEf
KEi + PEi = KEf
+
PEf
O J + mgh = KEf +
OJ
mgh = KEf
(3.00kg )(9.8 m/s2)(10m) = KEf
294 J = KEf
Solve:
KE = 294 J
__B__
63.
What is the kinetic energy of a 0.135 kg baseball thrown at 40.0 m/s?
a. 54.0 J
b. 108 J
c. 87.0 J
d. 216 J
Diagram: (Given + Unknowns)
Equation: KE = (1/2)mv2
m = .135 kg
v = 40 m/s
KE = ???? J
Substitute:
KE = (1/2)(.135kg)(40m/s)2
Solve:
_D___
64.
Old Faithful geyser in Yellowstone National Park shoots water every hour to a height of 40.0 m. With what velocity does the water leave
the ground? (Disregard air resistance.)
a. 7.00 m/s
b. 19.8 m/s
c. 14.0 m/s
d. 28.0 m/s
Diagram: (Given + Unknowns)
Equation: KEi + PEi = KEf + PEf
g =9.8 m/s2
h = 40 m
Substitute:
KEi=?
KEf = 0
top PE = mgh
KE = 0 J
bottom PE = 0 J
KE = ½mv2
KEi + PEi = KEf
+
PEf
½ mv2 + 0
= O J + mgh
½ mv2 = mgh
½ v2 = gh
½ v2 = (9.8 m/s2)(40m)
2
v
= 784
v = 28 m/s
m cancels
Solve:
__D__
28 m/s
=
v
An ice skater (mass of 75 kg), initially moving at 10.0 m/s, coasts to a halt in 1.0 x 102 m on a smooth ice surface. Find the force of
friction acting on the skater using the work-kinetic energy theorem.
a. 0.50 N
b. 37.5 N
c. -0.50 N
d. -37.5 N
Diagram: (Given + Unknowns)
Equation:
∆KE = work
(1/2)mv2 = fd
65.
m = 75 kg
v =10 m/s
d = 100 m
force F = ??? N
Substitute:
-(1/2)(75kg)(10 m/s)2 = F (100m)
-3750 = F (100 m)
-37.5 N = F
use the work-kinetic energy
theorem
_C___
KE = 108 J
Solve:
-37.5 N = F
since the object is slowing down.
66.
What is the average power supplied by a 60.0 kg student running up a flight of stairs rising vertically 4.0 m in 4.2 s?
a. 380 W
b. 610 W
c. 560 W
d. 670 W
Diagram: (Given + Unknowns)
Equation:
F = ma
W = fd
P = W/t
m = 60.0 kg
a =9.8 m/s2
d=4m
t=4.2 s
P = ???? Watt
F = ??? N
W = ??? J
Substitute:
F = ma
W = f(d)
P = W /t
F = 60.0 kg (9.8m/s2) = 588 N
W= 588 N (4 m) = 2352 J
P= 2352 J / 4.2 s = 560 Watt
Solve:
P = 560 Watt
__C__
67.
What is the average power output of a weight lifter who can lift 250 kg in 2.0 m in 2.0 s?
a. 5000 W
b. 4900 W
c. 2500 W
d. 9800 W
Diagram: (Given + Unknowns)
Equation:
F = ma
W = fd
P = W/t
Substitute:
m = 250 kg
a =9.8m/s2
d=2m
t=2.0 s
F = ??? N
W = ??? J
F = ma
W = f(d)
P = W /t
F = 250 kg (9.8m/s2) = 2450 N
W= 2450N (2 m) = 4900 J
P= 4900 J / 2 s = 2450 Watt
P = ???? Watt
__D__
P = 2450 Watts closest to 2500 Watts
Solve:
A roller coaster loaded with passengers has a mass of 2.0 x 103 kg; the radius of curvature of the track at the lowest point of the track is
24 m. If the vehicle has a tangential speed of 18 m/s at this point, what force is exerted on the vehicle by the track?
a. 2.3 x 104 N
b. 3.0 x 104 N
4
c. 4.7 x 10 N
d. 2.7 x 104 N
Diagram: (Given + Unknowns)
Equation:
ac = (Vt)2 / r
F= mac
68.
Circle
Fc = ???? N
m = 2000 kg
ac = ???? m/s2
vt =18 m/s
r = 24 m
Substitute:
ac = (18m/s)2 / 24 m = 13.5 m/s2
Fc = ma = 2000 kg(13.5 m/s2)
Solve:
__B__
Fc = 27000 N or 2.7 x 104N
What is the gravitational force between two trucks, each with a mass of 2.0 x 104 kg, that are 2.0 m apart?
a. 5.7 x 10–2 N
b. 6.7 x 10–3 N
–2
c. 1.3 x 10 N
d. 1.2 x 10–7 N
Diagram: (Given + Unknowns)
Equation:
69.
Fg = G m1m2 / d2
Gravitational Force
Substitute:
Fg = (6.67 x 10-11)(20000)(20000)/22
Fg = 6.7 x 10-3 N
Fg = ???? N
G = 6.67 x 10-11 N m2 / kg2
m1 = 20000 kg
m2 = 20000
d=2m
SOLVE:
Solve:
Fg = 6.7 x 10-3 N or 0.0067 N
_D___
70.
A 80.0 kg passenger is seated 12.0 m from the center of the loop of a roller coaster. What centripetal force does the passenger
experience when the roller coaster reaches an tangential speed of 37.7 m/s?
a. 1.7 x 103 N
b. 7.2 x 103 N
3
c. 6.9 x 10 N
d. 9.5 x 103 N
Diagram: (Given + Unknowns)
Equation:
Circle
ac = (Vt)2 / r
F= mac
Substitute:
Fc = ???? N
m = 80 kg
ac = ???? m/s2
vt =37.7 m/s
r = 12 m
ac = (37.7m/s)2 / 12 m = 118.4 m/s2
Fc = ma = 80 kg(118.4 m/s2)
Solve:
Fc = 9500 N or 9.5 x 103N
_B___
71.
If the distance from the center of a 10,000 kg merry-go-round to the edge is 1.2 m, what centripetal acceleration does a passenger
experience when the merry-go-round rotates at a speed of 1.5 m/s? (DRAW A PICTURE AND USE GUESS METHOD TO SOLVE)
a. 1.7 m/s2
b. 1.9 m/s2
c. 0.9 m/s2
d. 0.6 m/s2
Diagram: (Given + Unknowns)
Equation:
ac = (vt)2 / r
Circle
Substitute:
Fc = ???? N
m = 10,000 kg
ac = ????? m/s2
vt = 1.5 m/s
r = 1.2 m
ac = (1.5m/s)2 / 1.2 m = 1.9 m/s2
Solve:
Do not need to find centripetal force
_A___
72.
ac = 1.9 m/s2
When an object is traveled in a circular motion, the force is directed ___________________, the acceleration is directed
________________, and the velocity is directed ___________________________.
a. towards the center : towards the center: along a tangent of the circle
b. away from the center : away from the center: towards the center
c. along a tangent line : away from the center: towards the center
d.
towards the center: along a tangent of the circle: away from the center
73. On the following diagram, label the centripetal acceleration, centripetal force,
and the tangential velocity for the following whirling object.
74. Fill in the following table.
Quantity (Physics Term)
Symbol as used
in formulas
SI Unit
Quantity (Physics Term)
Symbol as
used in
formulas
SI Unit
Distance
d
m
Centripetal Acceleration
ac
m/s2
Displacement
Δd
m
Centripetal Force
Fc
N
Time
t
s
Tangential Velocity
vt
m/s
m/s
Radius
R
m
m/s
Torque
τ
J
Velocity
v
Speed
v
Initial Velocity
vi
m/s
Gravitational Potential
Energy
PEg
J
Final Velocity
vf
m/s
Elastic Potential Energy
PEelastic
J
Acceleration
a
m/s2
Kinetic Energy
KE
J
Force
F
N
Mechanical Energy
ME
J
Weight
Fg
N
Work
W
J
Mass
m
Kg
Energy
E
J
75. What is the weight of a 200 N puggle? ________200 N_____________________
76. What is the force of gravity on a 200 N puggle? _______200 N__________________
77. What is the mass of 200 N puggle? ___________20.4 kg___________