Spiral arms result from density waves in a disk galaxy. Star formation occurs in these arms. As the material in a galaxy interacts with a spiral density wave, clouds compress and dust lanes form. Then, the dense gas clouds ignite with star formation. What is the evidence in this image that supports the claim that the stars are moving faster than the density waves?

A. Bright stars can be found on the leading edges of the arms.

B. Bright stars are only found on the trailing edges of the arms.

C. Dust clouds form on the leading edges of the arms.

D. Ionization nebulae form on the trailing edges of the arms.

A B C D 14. A steel ball is dropped from a diving platform (with an initial velocity of zero). Using the approximate value of g = 10 m/s^2, what is its velocity 2.4 seconds after its release? a) 10, b) 2.4, c) 24, d) 4.2

A B C D 15. A large rock is dropped from the top of a high cliff. Assuming that air resistance can be ignored and that the acceleration has the constant value of 10 m/s^2. how fast would the rock be traveling 8 seconds after it is dropped in m/s? a) 40, b) 1.25, c) 18, d) 2.

A B C D 16. A ball is dropped from a high building. Using the approximate value of g = 10 m/s^2. find the change in velocity between the first and

fourth second of its flight in m/s. a) 30, b) 3.33, c) 13, d) 40

A B C D 17. A ball is thrown upward with an initial velocity of 12 m/s. Using the approximate value of g = 10 m/s^2, how high above the ground is the ball 2 seconds after it is thrown in meters? a) 12, b) 24, c) 6, d) 4.

A B C D 18. Suppose that the gravitational acceleration on a certain planet is only 3.0 m/s^2. A space explorer standing on this planet throws a ball straight upward with an initial velocity of 18 m/s. How much time in seconds elapses before the ball reaches the high point in its flight? a) 3, b) 6, c) 18, d) 54.

A B C D 19. A ball rolls off a shelf with a horizontal velocity of 5 m/s. At what horizontal distance in meters from the shelf does the ball land if it takes 0.4 s to reach the floor? a) 5.4, b) 2, c) 4.6, d) 1.25.

A skier with a mass of 75kg starts from rest at the top of a slope which is 110m tall and skis to the bottom. Hint: you must use conservation of energy to solve both parts of this problem. a. What is the skier’s speed at the bottom of the slope if there is no friction? b. If the speed of the skier at the bottom of the slope is actually 20m/s, how much work is done by friction?

Please I need a clear explanation and clear handwriting with explanaing this for me because I am realy confused and need help. Thanks in advance

My lab was about  Magnets and Magnetic fields. This is the question I need to answer for!

R3: Explain how a speaker works by explaining why each part is required. after that Summarize R3’s answer by explaining why the proffesor homemade earbud is so much superior to the one that you made.

How can I get density of state, Fermi energy, and total energy in 1,2 dimension when we have N electrons without interaction.

A metal sphere of radius 12 cm is charged using a rubber rod and acquires a charge of Q 1 = +5.8 μC. It is brought into contact with another metal sphere having a radius of 6.5 cm and an initial charge of Q 2 = +2.0 μC. After coming into contact, the two spheres are carefully separated. (a) What is the charge that ends up on each sphere after being in contact? (b) How many excess protons or electrons does each sphere end up with?

a ball is thrown up onto a roof, landing 3.60 s later at height h = 25.0 m above the release level. The ball's path just before landing is angled at ? = 64.0?with the roof. (a) Find the horizontal distance d it travels. (Hint: One way is to reverse the motion, as if it is on a video.) What are the (b) magnitude and (c) angle (relative to the horizontal) of the ball's initial velocity?

When two carts collide, we know that the total momentum of the system should be conserved, as long as there are no external forces acting on the system. That is, Pi = Pf, where Pi and Pf are the total momenta before and after the collision, respectively.

TOTALLY INELASTIC COLLISIONS

A. Carts with Equal Mass

Orient the carts so their Velcro bumpers face each other. In the collisions they MUST stick together.

1. Place one cart at rest in the middle of the track. Give the other cart an initial velocity toward the cart at rest.

2. Start with both carts at opposite ends of the track and push them toward each other with about the same speed.

3. Start with both carts at the same end. Give the first cart a slow initial speed, and the second a faster speed so it catches the first about half way down the track.

B. Carts with Unequal Mass

4. Place two mass bars on one of the carts. Now its mass is about 3 times the mass of the other cart. Put the 3M cart at rest in the middle of the track and push the other toward it.

5. Put the 1M cart in the middle and push the 3M cart toward it.

6. Start the carts at different ends of the track. Give them about the same speed toward each other.

7. Start both carts at the same end of the track. Give the 1M a slow speed, and the 3M a faster speed so that it collides with the first.

8. Start both carts at the same end of the track. Now give the 3M a slow speed, and the 1M a faster speed so that it collides with the first.

ELASTIC COLLISIONS

A. Carts with Equal Mass

Orient the carts so their magnetic bumpers face each other. The carts MUST bounce without hitting.

1. Place one cart at rest in the middle of the track. Give the other cart an initial velocity toward the cart at rest.

2. Start with both carts at opposite ends of the track and push them toward each other with about the same speed.

3. Start with both carts at the same end. Give the first cart a slow initial speed, and the second a faster speed so it catches the first about half way down the track.

B. Carts with Unequal Mass

4. Place two mass bars on one of the carts. Now its mass is about 3 times the mass of the other cart. Put the 3M cart at rest in the middle of the track and push the other toward it.

5. Put the 1M cart in the middle and push the other toward it.

6. Start the carts at opposite ends of the track. Give them about the same speed toward each other.

7. Start both carts at the same end of the track. Give the 1M a slow speed, and the 3M a faster speed so that it collides with the first.

8. Start both carts at the same end of the track. Now give the 3M a slow speed, and the 1M a faster speed so that it collides with the first.

A dog in a weight-pulling competition tugs a 50-kg sled a distance of 5 m across a snowy track. The dog pulls horizontally with a force of 350 N. The coefficient of kinetic friction between the sled and the snow is 0.05. (Draw yourself a free-body diagram on the sled). The next four questions have to do with this scenario.

Determine the work done by the dog.

I got the correct work (1750J)

Add up the y-components, ΣF_y, and determine the normal force the ground exerts upward on the sled.

Using your result from above, calculate the kinetic frictional force between the sled and the snowy track.

Determine the work done by friction.

A daring 51-kg swimmer dives off a 9-m high cliff. At the edge of the cliff her speed is 1.5 m/s. As the swimmer travels through the air, air resistance does -900 J of work on her. The next three questions have to do with this swimmer.

Which is the correct conservation of energy expression for this diving swimmer?

Using the appropriate conservation of energy expression, determine the kinetic energy of the swimmer as she safely enters the water at the bottom of the cliff.

Using your result from above, determine the swimmer's speed as she enters the water.

A 1.5-kg ball rolling to the right at a speed of 3 m/s collides with another ball of mass 3.0 kg rolling to the left at a speed of 2 m/s. As a result of the collision, the 1.5-kg ball recoils to the left at a speed of 1.5 m/s. (Draw yourself a before & after picture of this collision).  The next five questions have to do with this collision.

Calculate the momentum (magnitude and direction) of the 1.5-kg ball immediately before the collision.

Calculate the momentum (magnitude and direction) of the 3.0-kg ball immediately before the collision.

Calculate the momentum (magnitude and direction) of the 1.5-kg ball immediately after the collision.

Set up the conservation of momentum for this collision and determine the velocity (magnitude and direction) of the 3.0-kg ball immediately after the collision.

After the collision, the system's total kinetic energy is

1. Why must an IV bag be placed above a patient’s arm, but a syringe can be applied horizontally? PLEASE EXPLAIN THIS THOROUGHLY AND RELATE TO PHYSICS CONCEPTS

On emitting a photon, the hydrogen atom recoils to conserve momentum. Explain the fact that the energy of the emitted photon is less than the energy difference between the

energy levels involved in the emission process.

5-What is the maximum energy that can be transferred to an electron in a hard
collision by a 25-MeV (a) electron (according to convention), (b) positron, (c)
proton, (d) a-particle?
6-Redo problem 5 for the case where each of the particles has the same velocity
as a 25-MeV proton.

Redo problem 5 for the case where each of the particles has the same velocity as a 25-MeV proton.

Make a description of a Carnot engine considering the radiation of a black body as working substance. Verify Clausius relationship

37.44•• A Σ+Σ+ particle has a mean lifetime of 80.2 ps. A physicist measures that mean lifetime to be 403 ps as the particle moves in his lab. The rest mass of the particle is 2.12×10−27 kg.2.12×10−27 kg. (a) How fast is the particle moving? (b) How far does it travel, as measured in the lab frame, over one mean lifetime? (c) What are its rest, kinetic, and total energies in the lab frame of reference? (d) What are its rest, kinetic, and total energies in the particle’s frame?

1. A commercial airliner is flying at 450 mph, 20° east of north, relative to the surrounding air. The surrounding air though is blowing at 90 mph, 40° south of east, relative to the ground. The relative humidity of the air is 70%. How fast is the airliner flying relative to the ground, and in what direction?

2. Kenny and Cartman are playing paintball blindfolded. They are initially standing back-to-back, facing away from each other. Treat it as if they are standing on exactly the same spot. Kenny then runs 8 meters due west. Meanwhile, Cartman runs 2 meters due east, turns left, and runs 6 meters 30° east of north. They then turn around and start shooting paintballs. Of course, they are both blindfolded, so they aren’t coming anywhere close to hitting each other. How far apart are they when they start shooting?

3. Cartman decides to cheat, and peaks through his blindfold to see where Kenny is. He then turns and aims at Kenny. What direction does he need to aim in to hit Kenny? (relative to the cardinal axes, i.e. something like 40° south of west)