A professor sits on a rotating stool that spins at 10.0rpm while she holds a 1.00-kg weight in each of her hands. Her outstretched arms are 0.75m from the axis of rotation which passes through her head into the center of the stool. When she draws the weights in toward her body, her angular speed increases to 20.0 rpm. Neglecting the mass of her arms, how far are the weights from the rotational axis at the increased speed?

A natural water molecule (H2O) in its vapor state has an electric dipole moment of magnitude, p = 6.2 x 10-30 C.m. (a) Find the distance of the positive and negative charge centers of the molecule. Note that there are 10 electrons and 10 protons in a natural water molecule. (b) If the molecule is placed in a uniform electric field, E = 2 x 104 N/C find the maximum torque acting on the molecule. (c) How much work is needed to rotate this molecule by 180° in this field starting from the initial position, for which θ = 0? Hint: θ is the angle between the electric dipole moment and the electric field.

A monatomic ideal gas has an initial temperature of 381 K. This gas expands and does the same amount of work whether the expansion is adiabatic or isothermal. When the expansion is adiabatic, the final temperature of the gas is 290 K. What is the ratio of the final to the initial volume when the expansion is isothermal?

Using the kinematic data provided, calculate the masses, CoM coordinates, and moments of inertia (about the proximal end of the segment) for the foot and shank segments (mass: 48.1 kg) (knee: (0.268,0.499)) (ankle: (.240, 0.113)) (Met: (.359, 0.043))

Consider an object whose initial displacement and velocity are both equal to zero with respect to a reference point X. The object accelerates in a straight line away from X according to the following function of time: a(t) = 2t where the instantaneous acceleration is expressed in meters per second squared, and the initial time is t = 0. How fast is this object moving with respect to point X at t = 3 s?

A cylindrical steel tube 15.5 cm long and welded shut at one end holds 2.000 L at 23.0°C. It is completely filled with oil at 23.0°C. The oil and the tube are then slowly warmed together to 77.0°C. (The average linear expansion coefficient for metal is 2.4 x 10-5 °C−1, and the average volume expansion coefficient for oil is 9.0 x 10-4 °C−1.)

(a) How much oil overflows?

(b) What is the volume of oil remaining in the cylinder at 77.0°C?

(c) If the combination with this amount of oil is then cooled back to 23.0°C, how far below the cylinder's rim does the oil’s surface recede?

1. Explain why you can maintain contraction of the hamstring muscles over time.

2. Explain why you can sustain the same contraction with a 5-lb weight attached to the ankle.

3. Explain why the hamstring muscles fatigue faster with the 5-lb ankle weight.

4. State the order of recruitment of muscle fiber types.

Find the distribution of temperature inside a sphere of radius a when the surface of the upper half is held at 100°C and the surface of the lower half at 0°C

Describe the difference between an insulator and a conductor. What are some examples of each? Name some examples when you would want to use each of them.

John was swimming in the river. His swimming velocity was 1.2 m/s due east. The water was running at 0.4 m/s due west. John’s projected area in the water was 0.45 m2. Water density was 1000 kg/m3. The coefficient of drag was 0.2. (a) What was John’s velocity relative to the water? (b) What was the pressure drag force from the water? After a little while, John turned around and now is swimming at 1.2 m/s due west. (c) What is John’s velocity relative to the water now? (d) What is the pressure drag force from the water now? (e) What is the percentage of change in pressure drag force?

An object is placed 12 cm in front of a diverging lens with a focal length of 7.9 cm.

(a) Find the image distance and determine whether the image is real or virtual.

(b) Find the magnification

A 110-kg rugby player is sliding on a muddy field at a speed of 2 m/s toward the right as a 82-kg player is slipping at a speed of 3 m/s toward the left. As the two players collide, they grab onto each other and slide away together as one.

What kind of collision was this?

Set up the conservation of linear momentum for this collision, and determine the shared velocity (magnitude & direction) of the players immediately after the collision.

Would the players' total kinetic energy before the collision be equal to their total kinetic energy after? yes/no

a) Explain the production of x-rays

b) What is the typical energy range for Compton scattering and why?

c) Why does pair production require a minimal energy and what is it?

What is the energy released in this alpha decay reaction 23090Th?22688Ra+42He90230Th?88226Ra+24He? (The atomic mass of 230Th230Th is 230.033139 u and that of 226Ra226Ra is 226.025402 u)