1) Consider a soap bubble with radius, r. The pressure inside the bubble must be greater than the pressure outside of the bubble. The surface tension of the bubble, y, supports the difference in pressure, delta p. Using dimensional analysis, formulate an expression for the pressure difference.

2) In 1945 the first atomic bomb was tested in New Mexico. The destructive power (Energy) of the bomb was kept classified however, following the release of *time* stamped pictures showing the bomb's explosion *radius* a British physicist, G. I. Taylor, was able to estimate the power released by the explosion. Identify the missing parameter and use dimensional analysis to formulate an expression for the Energy.

A laser beam enters a 19.0 cm thick glass window at an angle of 39.0° from the normal. The index of refraction of the glass is 1.50. At what angle from the normal does the beam travel through the glass? Tries 0/20 How long does it take the beam to pass through the plate?

A solid nonconducting sphere of radius R = 5.7 cm has a nonuniform charge distribution of volume charge density ρ = (14.4 pC/m3)r/R, where r is radial distance from the sphere's center. (a) What is the sphere's total charge? What is the magnitude E of the electric field at (b) r = 0, (c) r = R/2.0, and (d) r = R?

A 56 g ice cube at -57°C is placed in a lake whose temperature is 33°C. Calculate the change in entropy of the cube-lake system as the ice cube comes to thermal equilibrium with the lake. The specific heat of ice is 2220 J/kg·K. (Hint: Will the ice cube affect the temperature of the lake?)

. In a device (figure 30-6) that is used to measure the maximum kinetic energy of photoelectric effect electrons, the voltage difference between the collector and emitter is increased until the current flowing through the circuit goes to zero. This is called the stopping potential and the KEmax can be very simply calculated if you use electron-volts. Using this device, you measure this voltage to be 0.710 V for electrons emitted from a surface illuminated by 492-nm light. Then, when you change the incident light to a new wavelength value, the new voltage is 1.41 V. a)What is the new wavelength? b) What is the work function for the surface?

an electron is moving with a speed of 2.9E5 m/s when it moves in the positive x direction, it feels no force. When it moves in the positive y direction it experiences a force of 3.3E-14N that points in the negative z direction. What is the magnitude and direction of the magnetic field?

Explain how an electric motor works. How does a stereo speaker use an electromagnet to produce sound? (10pts)

Due to the Doppler effect, a moving aircraft sees the broadcast signals at 377 MHz from a stationary communications antenna that broadcasts signals at 356 MHz. Find the relative velocity between the aircraft and the broadcast station. Determine the direction of the moving aircraft.

Speed amplifier. In the figure block 1 of mass m₁ slides along an x axis on a frictionless floor at speed 0.568 m/s. Then it undergoes a one-dimensional elastic collision with stationary block 2 of mass m₂ = 0.284 m₁. Next, block 2 undergoes a one-dimensional elastic collision with stationary block 3 of mass m₃ = 0.522 m₂. (a) What then is the speed of block 3? Compute ratios of (b) speeds, (c) kinetic energies, and (d) momentums for block 3 to block 1.

Question:
Consider a yo-yo as basically a string wound around a cylindrical disk. using terms like
torque, angular momentum, gravity, and conservation. Explain why the yo-yo begins to
roll down, why it will roll back up and lastly explain why it stops and then reverses.
Lastly, in the absence of any frictional loses as the rope unwinds and rewinds, and also
neglecting air resistance, would the yo-yo continue to forever?

The force table consists of a circular platform with marking at the edge showing the angle for a circle centered about the center of the table. A mass, m = 120 gram is places on a hanger which has a mass of 50 g, giving a total mass of 170 g. The hanger is hung at an angle of 110 deg over a pulley attached to the force table using a string of negligible mass. The pulley over which the string rests has very low friction force.

The tension in the string: 1.67  N.
The components: Fx = -0.570 N, Fy = 1.57 N
Total mass needed to balance the force: 170 g
Angle should the mass be hung: 290 deg.

This is where I'm confused and having problems:
The balancing mass used in the last exercise is kept in place. The original mass that was hanging at 110 deg is removed and replaced with its components with the x and y axes at 0 deg and the 90deg respectively. What is the total mass (mass plus hanger) needed along the x-axis? Along which direction should the mass be hung?
Mass = ??
I know that it will be -x from the Fx component

What is the total mass (mass plus hanger) needed along the y-axis? Along which direction should the mass be hung?
Mass = ??
I know that it will be +y from the Fy component

1. Measure and record the period of oscillation for the unknown mass m in a separate data table.

5 Points

2. Find the value of m using the equation for the spring oscillation, K= 27.63489231. Show all your calculation steps.

4 points

3. Find the value of m from the graph you did in 3 above. Describe how you did this.

4 points

4. Calculate the percent difference between the values in 6 and 7 showing all calculation steps.

A: A child, hunting for his favorite wooden horse, is running on the ground around the edge of a stationary merry-go-round. The angular speed of the child has a constant value of 0.297 rad/s. At the instant the child spots the horse, one-quarter of a turn away, the merry-go-round begins to move (in the direction the child is running) with a constant angular acceleration of 0.00500 rad/s². What is the shortest time it takes for the child to catch up with the horse?

B:The earth spins on its axis once a day and orbits the sun once a year (365.24 days). In each case take the positive direction for the angular displacement to be the direction of the earth's motion.

Determine the average angular velocity of the earth as it spins on its axis.


Determine its angular velocity as it revolves around the sun.