Proof the equation of number of holes in VB at intrinsic Semiconductor

A straight metal wire is placed between the poles of a magnet, as shown in the figure. Magnetic field is uniform in the space between the poles. If there is a current I flowing through this wire in the direction from C to A, what is the direction of the magnetic force acting on the wire?

in air track experiments, we assume that kinetic friction between the ait track and the car is negligible. If friction is not negligable, how would the friction affect each of the following

A) velocity of the car

B) kinetic energy of the car

C) potential energy of the car

D) mechanical energy of the car

As shown below, a 100 kg student is compressed 50 cm on a spring with a spring constant of k = 80,000 N/m. He is on top of a 10 m frictionless hill. He then is released from rest. He goes down to the bottom of the hill before sliding up a 30° frictionless hill. a. (8 pts) Find the speed of the student when he reaches the bottom of the hill. b. (9 pts) Find the distance D the student travels up the hill before momentarily stopping. Use whichever method you wish.

A cooling fan is turned off when it is running at 840 rev/min . It turns 500 revolutions before it comes to a stop.

1.) What was the fan's angular acceleration, assumed constant?

2.) How long did it take the fan to come to a complete stop?

A) A 12.0-g bullet is fired horizontally into a 113-g wooden block that is initially at rest on a frictionless horizontal surface and connected to a spring having spring constant 149 N/m. The bullet becomes embedded in the block. If the bullet-block system compresses the spring by a maximum of 76.0 cm, what was the speed of the bullet at impact with the block?

B)A 0.033-kg bullet is fired vertically at 238 m/s into a 0.15-kg baseball that is initially at rest. How high does the combined bullet and baseball rise after the collision, assuming the bullet embeds itself in the ball?

Explain and solve the following physics question.

An alpha particle with kinetic energy 14.0 MeV makes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude L=p0b, where p0 is the magnitude of the initial momentum of the alpha particle and b=1.20×10⁻¹² m . (Assume that the lead nucleus remains stationary and that it may be treated as a point charge. The atomic number of lead is 82. The alpha particle is a helium nucleus, with atomic number 2.)

1. What is the distance of closest approach? Find r. (meters)

2. Repeat for b =1.30×10⁻¹³ m. Find r. (meters)

3. Repeat for b =1.30×10⁻¹⁴ m. (meters)

A rider on a Ferris wheel shown below travels at a constant speed. Is the rider’s apparent weight of the rider greater at the top or the bottom? Explain using physical reasoning and FBDs if necessary.

Calculate the length of a Kerr cell using carbon disulphide required to produce half wave retardation for an applied voltage of 30kV. The electrodes of this cell have a separation of 1.5 cm. Is this cell practical? Repeat the calculation, this time the carbon disulphide being replaced by 4-cyanophenyl 4-pentylbenzoate. Use values given in the notes. Is this cell practical?
Carbon disulphide CS2 3.5 × 10-12 cmV-2 .
4-cyanophenyl 4-pentylbenzoate 9537 × 10-12 cmV-2 at 63.9ºC.

An elevator at the bottom of a 80 foot shaft weighs 1500 pounds. The 80 foot cable that lifts the elevator weighs 400 pounds. Assume that the cable has uniform weight over its length. Answer the following questions to calculate the work that is done to raise the elevator 50 feet up from the bottom of the shaft. (a) Write a Riemann sum that approximates the work needed to lift the 50 ft up the shaft. (b) Write and evaluare an integral to calculate the work done to raise the cable 50 ft up the shaft. (c) What is the total work required to lift the cable and elvator 50 ft up the shaft?

Create a plot comparing the force applied to an object versus the angle at which the force is applied. Alos, plate describe the graph in paragraph form.

A tourist being chased by an angry bear is running in a straight line toward his car at a speed of 3.36 m/s. The car is a distance d away. The bear is 26.7 m behind the tourist and running at 4.51 m/s. The tourist reaches the car safely. What is the maximum possible value for d?

A circular coil (radius = 0.40 m) has 160 turns and is in a uniform magnetic field. If the orientation of the coil is varied through all possible positions, the maximum torque on the coil by magnetic forces is 0.16 Nm when the current in the coil is 4.0 mA. What is the magnitude of the magnetic field?

Consider a stationary solution of the Schrodinger Equation with positive energy E for a particle with mass m in the following one-dimensional potential: V (x) = 0 for |x| > a and V (x) = −V0 for |x| ≤ a with V0 > 0. (a) Calculate the transmission and reflection probabilities. (b) Show that the transmission probability is unity for some values of the energy.