What is the wavelength of the -Hz radio wave used by “radio-controlled” clocks and wristwatches?​

(Explain using the law of conservation of momemtum)   When a ball strikes the floor and rebounds, it appears that momentum is not conserved. Is this true? Why or why not?

A 120 kg crocodile swallows gastrolithes that are 0.8% of his mass to sink to a lower level. How much would it have to increase its lung volume in mL to counteract the sinking effect? Assume that the air pressure in its lungs is not much greater than atmospheric pressure.

The 25-lb slender rod has a length of 6 ft. Using a collar of negligible mass, its end A is confined to move along the smooth circular bar of radius 32√ ft. End B rests on the floor, for which the coefficient of kinetic friction is μB = 0.28. The bar is released from rest when θ = 30∘.

Determine the angular acceleration of the bar at this instant, measured clockwise.

A 60 kg sofa 4m long is carried by James and Sarah. James is holding the sofa 0.2m from an end. Sarah is holding the sofa by the other end. A passing moron places a 40 kg box of books on the sofa 0.5m from the end Sarah is holding. How much weight is sarah holding now.

A bowling ball rolls without slipping up a ramp. If the speed at the bottom of the ramp is 2.85 m/s and the height of the ramp is 0.525 m, what is the speed of the ball at the top of the ramp?

A long time ago, in a galaxy far, far away, electric charge had not yet been invented, and atoms were held together by gravitational forces. Compute the Bohr radius (a₀) and the

n = 5 to n = 2

transition energy

(E₅ − E₂)

in a gravitationally bound hydrogen atom.

A weightlifter works out at the gym each day. Part of her routine is to lie on her back and lift a 41 kg barbell straight up from chest height to full arm extension, a distance of 0.55 m .

1. How much work does the weightlifter do to lift the barbell one time?

2. If the weightlifter does 25 repetitions a day, what total energy does she expend on lifting, assuming a typical efficiency for energy use by the body (25%).

3. How many 430 Calorie donuts can she eat a day to supply that energy? Express your answer using two significant figures.

The wave function for hydrogen in the 1s state may be expressed as ψ(r) = Ae−r/a0. Determine the normalization constant A for this wave function. (Use the following as necessary: a0.)

A pendulum clock in an elevator ticks with a period of T=1.7 s when the elevator is at rest. The elevator starts to move and the period increases to Tnew = 1.87 s.

1. How is the elevator moving? Select the correct answer:

a) accelerating, upward

b) accelerating, downward

c) constant speed, upward

d) constant speed, downward

2. Identify the correct acceleration for the elevator. You must show your work to get credit for your selection.

a) 1.7 m/s^2

b) -0.89 m/s^2

c) 2.06 m/s^2

d) 0.89 m/s^2

e) -1.7 m/s^2

You attach a 100-g puck to a string and let the puck glide in a circle on a horizontal, frictionless air table. The other end of the string passes through a hole at the center of the table. You pull down on the string so that the puck moves along a circular path of radius 0.50 m. It completes one revolution in 6.0 s.

If you pull harder on the string so the radius of the circle slowly decreases to 0.40 m, what is the new period of revolution?

Tf =

A 1.5 kg solid cylinder (radius = 0.15 m , length = 0.60 m ) is released from rest at the top of a ramp and allowed to roll without slipping. The ramp is 0.80 m high and 5.0 m long.

When the cylinder reaches the bottom of the ramp, what is its total kinetic energy?

When the cylinder reaches the bottom of the ramp, what is its rotational kinetic energy?

When the cylinder reaches the bottom of the ramp, what is its translational kinetic energy?

A solid disk of mass M and radius R is rotating on the vertical axle with angular speed w. Another disk of mass M/2 and radius R, initally not rotating, falls coaxially on the disk and sticks. The rotational velocity of this system after collision is:

w

w/2

2w/3

3w/2

2w

A point charge with a mass of 1.81 ng and a charge of +1.22 uC moves in the x-y plane with a velocity of 3.00 x 104 m/s in a direction 15° above the +x-axis. At time t=0, the point charge enters a uniform magnetic field of strength 1.25 T that points in the +x-direction. Assume that the point charge remains immersed in the uniform magnetic field after time t=0.

a. (5 points) What is the magnitude and direction of the magnetic force that the magnetic field exerts on the point charge at time t=0?

b. (5 points) How does the x-component of the charge’s initial velocity effect the motion of this point charge as it moves through the uniform magnetic field? Does its magnitude change? Does its direction change? Explain your reasoning.

c. (5 points) How does the y-component of the charge’s initial velocity effect the motion of this point charge as it moves through the uniform magnetic field? Does its magnitude change? Does its direction change? Explain your reasoning.

d. (5 points) Use your answers from parts 1b & 1c to explain why the path of this point charge is helical (corkscrew-shaped). Explain your reasoning.

e. (2.5 points) Determine the radius of the circular part of the point charge’s helical path.

Let me know the effectiveness of the death penalty?
Are there alternative punishments that would be more effective than the death penalty?