sulmankhursheed56

A 0.38 {\rm kg} pendulum bob is attached to a string 1.2 {\rm m}long.

What is the change in the gravitational potential energy of thesystem as the bob swings from point A to point B in thefigure
Express your answer using two significant figures.
\Delta U =


{\rm J}
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A 1300 kg. wrecking ball hangs from a 12 m -long cable. The ballis pulled back until the cable makes an angle of 28.0 with thevertical.
By how much has the gravitational potential energy of the ballchanged? ΔU=_________
Express your answer to two significant figures and include theappropriate units.

Just a few questions from a review packet i'm stuck on, anyhelpwould be appreciated!

1) The moment of inertia about its axis is given as .5 mr^2. Ifthiscylinder rolls without slipping the ratio of it's rotationalkineticenergy to it's translational kinetic energy is
a. 2:1
b. 1:1
c. 1:2
d. 1:3

2) An object’s angular momentum changes by 20 kg,m2/s in 4.0s. Whatmagnitude average torque acted on this object?
A. 2.5 N’m
B. 5.0 N-m
C. 40 N-m
D. 80 N’m

3) A solid cylinder of mass 10 kg is pivoted about africtionlessaxis thought the center O. A rope wrapped around theouter radiusR1 = 1.0 m, exerts a force F1 = 5.0 N to the right. Asecond ropewrapped around another section of radius R2 = 0.50 mexerts a forceF2 = 6.0 N downward. (See Fig. 8-1.) What is theangularacceleration of the cylinder?
A) 1.0 rad/s2
B) 0.60 rad/s2 >my guess<
C) 0.40 rad/s2
D) 0.80 rad/s2

4) A solid sphere of mass 1.0 kg and radius 0.010 m starts fromrestand rolls without slipping down a 1.0-m high inclined plane.What isthe speed of the sphere when it reaches the bottom of theinclinedplane?
A) 3.7 m/s >My guess<
B) 4.4 m/s
C) 5.6 m/s
D) 6.3 m/s

5)A railroad car with a mass of 200 kg is going at 10 m/s. A 70kgstunt man drops directly down on it from a distance of 4 mabove.What is the speed of the railroad car after?
a. 4.7 m/s
b. 7.4 m/s
c. 2.8 m/s
d. 10 m/s

6) A projectile is launched with an initial velocity of 60 m/s atanagnle of 30 degrees above the horizontal. How far will itgo?
a. 318 m
b. 160 m
c. 152 m
d. 184 m

Ø   What happened to HRM beginning and growth in Ethiopia?

A 1300 kg. wrecking ball hangs from a 12 m -long cable. The ball ispulled back until the cable makes an angle of 28.0 with thevertical.
By how much has the gravitational potential energy of the ballchanged? ΔU=_________
Express your answer to two significant figures and include theappropriate units.


Can you please help or check the answer...I was marked wrong when Iput this answer in 2 sig figs

= 1.5*10^{3 J}

RE: change in gravitational potential energy
Answer Details
when the ball is mean position that means horizontal (h = 0) thenthe intial potential energy,
P.Ei = mgh = 0
if the ball is reaches height 'h' then the final potentialenergy,
P.Ef = mgh = mgl(1-casθ) = 1300*9.8*0.117
= 1491.24 J
therefore ΔP = Pef-Pei =1491.24 J

6. A 150 kg hoop rolls down an inclined with an initial potentialenergy U = 12 J . What will be the speed of the hoop's centerof
mass when it reaches the horizontal plane? (Assume that thefrictional force is negligible.) [Answer: 0.283 m/s]

A disk and a hoop of the same mass and radius are released at thesame time at the top of an inclined plane. Which object reaches thebottom of the incline first?

A) the hoop
B) the disk
C) they both reach the bottom at the same time
D) It depends of the angle of the inclination

1) Two children, A and B, are riding on a rotating merry-go-round.Child A is at a greater distance from the axis of rotation thanchild B. Which child has the larger tangential speed?
a) Child A
b) Child B
c) They have the same zero tangential speed.
d) They have the same non-zero tangential speed.
e) There is not enough information given to answer thequestion.
2) A disk and a hoop of the same mass and radius are released atthe same time at the top of an inclined plane. Which object reachesthe bottom of the incline first?
(I disk = .5MR^2 and I hoop = MR^2)
a) The hoop
b) The disk
c) Both reach the bottom at the same time
d) It depends on the angle of inclination.
e) It depends on the length of the inclined surface.
3) Two equal forces are applied to a door. The first force isapplied at the midopint of the door; the second is applied at thedoorknob. Both forces are applied perpendicular to the door. Whichforce exerts the greater torque?
a) the first at the midpoint
b) the second at the doorknob
c) both exert equal non-zero torques
d) both exert zero torques
e) additional information is needed
4) A merry-go-round spins freely when Janice moves quickly to thecenter along a radius of the merry-go-round. It is true to saythat_
a) the moment of inertia of the system decreases and the angularspeed increases.
b) the moment of inertia of the system decreases and the angularspeed decreases.
c) the moment of inertia of the system decreases and the angularspeed remains the same.
d) the moment of inertia of the system increases and the angularspeed increases.
e) the moment of inertia of the system increases and the angularspeed decreases.
5) An astronaut is in a capsule in a stable orbit, about two Earthradii from the center of Earth. Her weight is_
a) zero N
b) the same as on the surface of Earth
c) about 1/2 of her weight on the surface of Earth
d) about 1/3 of her weight on the surface of Earth
e) about 1/4 of her weight on the surface of Earth
6) Planet Z-34 has a mass equal to one-third that of Earth and aradius equal to one-third that of Earth. With g representing, asusual, the acceleration due to gravity on the surface of Earth, theacceleration due to gravity on the surface of Z-34 is_
a) g/3
b) 3 g
c) 6 g
d) g/9
e) 9 g
7) How does the escape speed from Mars compare with that of theEarth?
(M Earth = 9.31 * M Mars; R Earth = 1.88 * R Mars)
a) 222%
b) 22.5%
c) 44.9%
d) 66.2%
e) 20.2%
8) A mass on a spring undergoes simple harmonic motion. When themass is at its maximum displacement from equilibrium, itsinstantaneous velocity_
a) is maximum
b) is less than maximum, but not zero
c) is zero
d) cannot be determined without mass information given
e) cannot be determined without spring constant informationgiven
9) The total mechanical energy of a simple harmonic oscillatoris_.
a) zero as it passes the equilibrium point
b) zero when it reaches the maximum displacement
c) a maximum when it passes through the equilibrium point
d) a minimum when it passes through the equilibrium point
e) constant

What are the major challenges and potential solutions for achieving long-term sustainable energy systems that can effectively mitigate climate change and reduce greenhouse gas emissions on a global scale? Please provide a detailed analysis considering different energy sources, technologies, policies, and societal factors involved.

In the example 12.5 (Section 12.3) in the textbook we ignored thegravitational effects of the moon on a spacecraft en route from theearth to the moon. In fact, we must include the gravitationalpotential energy due to the moon as well. For this problem, you canignore the motion of the earth and moon.

Part A
If the moon of mass m_{\rm M} has radius R_{\rm M} and the distancebetween the centers of the earth and the moon is R_{\rm EM}, findthe total gravitational potential energy of the particle-earth andparticle-moon systems when a particle with mass m is between theearth and the moon, and a distance r from the center of the earth.Take the gravitational potential energy to be zero when the objectsare far from each other. Take the mass of earth as m_{\rm E}.

Part B
There is a point along a line between the earth and the moon wherethe net gravitational force is zero. Use the expression derived inpart (a) to find the distance of this point from the center of theearth.

Part C
With what speed must a spacecraft be launched from the surface ofthe earth just barely to reach this point?

Part D
If a spacecraft were launched from the earth's surface toward themoon with an initial speed of 11.2 {\rm km/s}, with what speedwould it impact the moon?

at a point between the earth and the moon, the magnitude of theforce exerted on an object by the earth's gravity equals themagnitude of the force exerted on the object by the moon's gravity.what is the distance from the center of the earth to thispoint?

distance from center of earth to center of moon = 383000 km
radius of earth= 6370 km
radius of moon=1738 km
acceleration due to gravity for the moon = 1.62 m/s^2

A spacecraft is on a journey to the moon. At what point, as measuredfrom the center of the earth, does the gravitational force exerted onthe spacecraft by the earth balance that exerted by the moon? Thispoint lies on a line between the centers of the earth and the moon. Thedistance between the earth and the moon is 3.85 × 108 m, and the massof the earth is 81.4 times as great as that of the moon.

3. As astronauts consider how to better study Excalibur, they reflect on some of the probes they have used in our own solar system. They recall a probe that they released from a spacecraft onto the moon. The probe sends signals to a transmitter on the spacecraft. Assuming that the probe and transmitter are 10m apart and they have no initial charge, what negative charge must be transferred to the probe to create an attractive force between them of 200N? (Show your work) (5 points)

4. Using your knowledge of Newton's Universal Law of Gravitation and Coulomb's Law, compare and contrast them. How are they similar? How are they different? (5 points)

Looking through the novel Night we see the term of Night repeated throughout the story.

Identify all of the uses of night and how you

would define them. Use a paragraph for each explanation

B) Write about the significance of Elie not only repeating the term but also why you believe the novel took it on as a title.