Physics 2

1. A 7.5 kg box that has an initial speed of 4.0 m / s slides along a rough board and reaches rest. Estimate the total change in the entropy of the universe. Assume that all objects are at room temperature (293 K)

2. What is the efficiency of a Carnot engine that is operating between a hot reserve at 800 K and a cold reserve at 400 K?

What is the mass of a baseball if the kinetic energy is 122 J when the baseball is thrown at 103 mph? (in grams)

A batter hits a pop fly, and the baseball reaches an altitude of 230 ft. If we assume that the ball was 3 ft. above home plate when hit by the batter, what is the ball's increase in potential energy? (in joules)

This question is inspired by this question/answer pair: Is this formula for the energy of a configuration of 3 fluids physically reasonable?

Consider three immiscible fluids forming contact surfaces, where none of the three can make a lubrication layer for the other two (the surface energy between fluid 1 and fluid 2 is not decreased by putting a thin layer of fluid 3 inbetween them, and likewise for the other two permutations). In this case, if all the contact surface tensions are positive, you have a minimum energy when all the surfaces are flat.

But there is a separate line tension for the 3-fluid interface itself. Can this line tension be negative? If it is negative, the line would like to wriggle, but the surface tension will require that the wriggles straighten themselves out as quickly as possible, to make the surface energy least. In this case, the minimizing energy configuration seems to be a very rapidly wriggling curve which is only infinitesimally different at the atomic scale from straight line. This suggests that a negative line-tension always renormalizes to exactly zero line-tension at long wavelengths. Is this correct?

Are there experimental or computational 3-phase line interfaces with a negative line tension? Do they renormalize to a zero line tension limit? Does this mean that zero line tension is a common observation?

A wire 109.0 cm long lying along the x axis carries a current of 360.0 mA in the positive x direction, through a magnetic field B = (0.0048 T)i + (0.0036 T)j + (0.0007 T)k. Find the magnitude of the force on the wire.

Question #1

What is the ratio of the suns gravitational force on you to the earths gravitational force on you?

Please slove this by step by step and explain the steps. Thank you.

Question #2

A)What is the gravitational force of the sun on the earth?

B) What is the gravitational force of the moon on the earth?

C) The moon's force is what percent of the suns force?

Please slove this by step by step and explain the steps. Thank you.

An astronaut standing on the surface of Ceres, the largest asteroid, drops a rock from a height of 10m. It takes 8.06s to hit the ground. Calculate the acceleration of gravity on Ceres. Find the mass of Ceres, given the radius is 510km. Calculate the gravitational acceleration 50km from the surface of Ceres.

a. Calculate the acceleration of gravity on Ceres.

b. Find the mass of Ceres, given the radius is 510km.

c. Calculate the gravitational acceleration 50km from the surface of Ceres

A fixed 17.1-cmcm-diameter wire coil is perpendicular to a magnetic field 0.70 TT pointing up. In 0.16 ss , the field is changed to 0.34 TT pointing down. What is the average induced emf in the coil?

Newton said that objects continue moving if no forces are acting on them, but his predecessor Aristotle said that a force was necessary to keep an object moving. Why does Aristotle’s theory seem more plausible, even though we now believe it to be wrong? What insight was Aristotle missing about the reason why things seem to slow down naturally? Give an example

11. Six 2-ohm resistors are placed in series and connected across a 12-volt battery’s terminals. The voltage I cannot easily obtain from this system is

(a) 3V

(b) 6V

(c) 9V

(d) 12V

Two 2 microfarad capacitors are connected in series and the combination placed across the terminals of a 12 V battery. What charge will appear on their positive plates?

(a) 1 μC

(b) 2 μC

(c) 4 μC

(d) 12 μC

Can someone explain these questions

The picture tube in an old black-and-white television uses magnetic deflection coils rather than electric deflection plates. Suppose an electron beam is accelerated through a 54.0-kV potential difference and then through a region of uniform magnetic field 1.00 cm wide. The screen is located 10.2 cm from the center of the coils and is 48.6 cm wide. When the field is turned off, the electron beam hits the center of the screen. Ignoring relativistic corrections, what field magnitude is necessary to deflect the beam to the side of the screen?

An electron with a speed of 1.3 ×106m/s collides with an atom of element X. Shortly afterward, the atom emits a 1240 nm photon. What was the electron's speed after the collision? Assume that, because the atom is so much more massive than the electron, the recoil of the atom is negligible. Hint: The energy of the photon is not the energy transferred to the atom in the collision.

Question 2: (2pts) Prediction of Gravitational, Kinetic and Total energy for a bouncing ball. Based on your predictions of position and velocity vs time, explain how the energy changes during the motion of the ball. (a) Where on your position vs. time graph is the Gravitational Potential Energy at a maximum during each bounce? Where is it a minimum? What is the velocity when the gravitational potential energy is maximum? What about when the gravitational potential energy is minimum? Explain your reasoning below. (b) Where on your velocity vs time graph is the Kinetic Energy at a maximum? Where is it a minimum? What is the vertical position of the ball when the kinetic energy is a maximum? What is the vertical position when the kinetic energy is a minimum? Explain your reasoning below.

2.0 kg of solid gold (Au) at an initial temperature of 1000 K is allowed to exchange heat with 1.5 kg of liquid gold at an initial temperature at 1336 K. The solid and liquid can only exchange heat with each other. When the two reach thermal equilibrium will the mixture be entirely solid, or will they be in a mixed solid/liquid phase? Explain how you know

2 blocks slide towards each other on a frictionless horizontal surface. Block A slides from left to right at a speed of 3m/s. It's mass is 2kg. Block B slides from right to left at a speed of 5 m/s. It's mass is 1 kg. They stick together upon collision.

1. Find the change of momentum of block A.

2. Find the change in momentum of block B.

3. Find the change in kinetic energy of the 2 block system due to the collision.

4. Find the final velocity of the blocks after collision.

5. If the time required for the collision to occure is 5 milliseconds, Find the average force exerted during the collision on block A.

A mass spectrometer is used to examine the isotopes of uranium. Ions in the beam emerge from the velocity selector at a speed of 3.08 ✕ 10⁵ m/s and enter a uniform magnetic field of 0.590 T directed perpendicularly to the velocity of the ions. What is the distance between the impact points formed on the photographic plate by singly charged ions of ²³⁵U and ²³⁸U?
cm