Water standing in the open at 34.5°C evaporates because of the escape of some of the surface molecules. The heat of vaporization (553 cal/g) is approximately equal to εn, where ε is the average energy of the escaping molecules and n is the number of molecules per gram. (a) Find ε. (b) What is the ratio of ε to the average kinetic energy of H₂O molecules, assuming the latter is related to temperature in the same way as it is for gases?

A spherical conductor has a radius of 14.0 cm and a charge of 26.0 µC.

Calculate the electric field and the electric potential at:

(a) r = 10.0 cm,

(b) r = 20.0 cm,

(c) r = 14.0 cm from the center.

A contestant in a winter games event pushes a 46.0 kg block of ice across a frozen lake as shown in the figure below. The coefficient of static friction is 0.1 and the coefficient of kinetic friction is 0.03. (Assume θ = 25°.) (a) Calculate the minimum force F (in N) he must exert to get the block moving. 49.7 Correct: Your answer is correct. N (b) What is its acceleration (in m/s2) once it starts to move, if that force is maintained? Incorrect: Your answer is incorrect. Consider Newton's Second Law. m/s2

The ammonia molecule NH₃ has a permanent electric dipole moment equal to 1.47 D, where 1 D = 1 debye unit = 3.34 × 10^-30 C-m. Calculate the electric potential in volts due to an ammonia molecule at a point 49.6 nm away along the axis of the dipole. (Set V = 0 at infinity.)

Answer following questions:

a) Explain the difference between an isotropic material and an anisotropic material. Give one example of abiological material other than bone that is anisotropic and explain how it is anisotropic.

b) It is well documented that humans are typically taller first thing in the morning, but get progressively shorter (by very small amounts) as the day goes on. Based on what you know about the viscoelastic properties of human body tissues, can you explain this phenomenon?

c) Explain how the creep response of a viscoelastic material is different than the stress-relaxation response of that material. Provide an example of one biological material for which creep is a significant issue to deal with and one biological material for which stress-relaxation is a significant issue to deal with.

Ball Thrown upward with an initial speed of 14.7m/s from a height of 89m

a)Draw the sketch of this motion

b) State the theory that describes this motion

c) Write the velocity and position kinematics equations with the number obtained from the sketch

d) Solve all unknowns

- Final velocity

- How long it takes that ball hit the ground

- Maximum Height

- Acceleration (I think its gravity)

e) Draw the velocity vs time and position vs time graphs

An object 9.0 cm tall is 45 cm in front of a convex mirror with a radius of curvature of 45 cm.

A) Where is the image? distance

B) How big is it?

C) Construct a ray diagram to scale. Indicate the parallel, focal, and central rays in your diagram

A uniform electric field of magnitude 240 V/m is directed in the positive x direction. A +13.0 µC charge moves from the origin to the point (x, y) = (20.0 cm, 50.0 cm). (a) What is the change in the potential energy of the charge field system? J (b) Through what potential difference does the charge move?

1. Typical household currents are on the order of a few amperes.

a. If a 1.54A current flows through the leads of an electrical appliance, how many electrons per second pass through it?

b. If a 1.54A current flows through the leads of an electrical appliance, how many coulombs pass through it in 5.50 min?

c. If a 1.54A current flows through the leads of an electrical appliance, how long does it take for 7.24C of charge to pass through?

d. A copper transmission cable 170km long and a 12.5cm in diameter carries a current of 135 A. What is the potential drop across the cable?

The lightbulb has a different dynamic resistance depending on whether the voltage is increasing or decreasing. Explain why the dynamic resistance is different under these two conditions.

Everyone knows that an earthquake is the shaking of the ground. Describe the ways in which it acts like a wave. How can the S and P waves be used to determine the location of the epicenter and the nature of the interior of the Earth?

Two small nonconducting spheres have a total charge of Q=Q1+Q2= 90.0 μC , Q1<Q2. When placed 31.0 cm apart, the force each exerts on the other is 13.0 N and is repulsive.

Part A: What is the charge Q1?

Part B: What is the charge Q2?

Part C: What would Q1 be if the force were attractive?

Part D: What would Q2 be if the force were attractive?

A tourist is driving a car along a straight road at a constant speed of 22.5 m/s. Just as she passes a law officer parked along the side of the road, the officer starts to accelerate 2.50 m/s² to overtake her. Assume that the officer maintains this acceleration.

(a) Determine the time it takes the officer to reach the tourist (in s).

18 s

(b) Find the speed of the officer as he overtakes the tourist (in m/s).

  45 m/s

(c) Find the total displacement of the officer as he overtakes the tourist (in m).

  405 m

(d) What If? Determine the answers to parts (a) through (c) of the problem, if instead of accelerating at the same instant the car passes him, the officer instead begins his acceleration 1.00 s after the car passes him. (Enter the time in s, speed in m/s, and displacement in m.)

time _____s

speed ____m/s

displacement _____m

A long wire carrying a 5.8 A current perpendicular to the xy-plane intersects the x-axis at x=−1.7cm. A second, parallel wire carrying a 2.0 A current intersects the x-axis at x=+1.7cm. A. At what point on the x-axis is the magnetic field zero if the two currents are in the same direction? B. At what point on the x-axis is the magnetic field zero if the two currents are in opposite directions?