Gina pushes a book across a table at constant speed. Fatima lowers a book from a high shelf down to her waist, where it comes to rest. Isidra holds a book at her waist while carrying it up stairs. Jin holds a book at her waist while carrying it across the room at constant speed. Who does zero work on their book?

A. Gina

B. Fatima

C. Isidra

D. Jin

A 3.9 kg mass is connected to a spring (k=179 N/m) and is sliding on a horizontal frictionless surface. The mass is given an initial displacement of +18 cm and released with an initial velocity of -16 cm/s. Determine the acceleration of the spring at t=1.9 seconds. (include units with answer)

To understand the concept of reactance (of an inductor) and its frequency dependence.

When an inductor is connected to a voltage source that varies sinusoidally, a sinusoidal current will flow through the inductor, its magnitude depending on the frequency. This is the essence of AC (alternating current) circuits used in radio, TV, and stereos. Circuit elements like inductors, capacitors, and resistors are linear devices, so the amplitude I0 of the current will be proportional to the amplitude V0 of the voltage. However, the current and voltage may not be in phase with each other. This new relationship between voltage and current is summarized by the reactance, the ratio of voltage and current amplitudes, V0, and I0: XL=V0/I0, where the subscript L indicates that this formula applies to an inductor.

What is the reactance XL of an inductor?

The speed of sound in seawater is approximately 1480 m/s. You are at a depth of 50.0m a. You ping the ocean bottom and receive the echo back 0.125 seconds later. How deep is the ocean at this point? b. If the frequency of the sound is 500.0 Hz, what is the wavelength of the sound? c. The ping coming back to the submarine has an intensity of as -80.0 dB. What is the intensity of the returning sound wave? d. Use the distance in part (b) and the answer in (c) to find the power of the reflected sound.

. Active sonar is used to determine the speed of an oncoming submarine. You send out a signal with a frequency of 500.0Hz. Your submarine is traveling at 13.0 m/s and the enemy is coming towards you at 9.00 m/s. Use the wave i.e. speed of sound as 1480m/s. a. What frequency will be reflected off the enemy? b. What frequency will be received by your submarine from the reflection? c. The enemy stops and sends his own signal of 600.0Hz. You receive his signal at what frequency? You are still moving towards him.

Assume air resistance is negligible unless otherwise stated.

Calculate the displacement in m and velocity in m/s at the following times for a rock thrown straight down with an initial velocity of 13.2 m/s from the Verrazano Narrows bridge in New York City. The roadway of this bridge is 70.0 m above the water. (Enter the magnitudes.)

(a)

0.500 s

displacement m

velocity m/s

(b)

1.00 s

displacement m

velocity m/s

(c)

1.50 s

displacement m

velocity m/s

(d)

2.00 s

displacement m

velocity m/s

(e)

2.50 s

displacement m

velocity m/s

Considering the illustrations for Concave and Convex mirrors.

Prove using geometry that the reflected rays reach the focal point f=R/2 in the limit as the incoming rays approach the principal axis.

Hint: Consider the triangle formed by the radius of curvature, principal axis, and reflected ray, and use the law of sines.

1.Check your car and find some electric/magnetic components, explain their working principle from physics. Such as battery, generator, alternator, starter, speed sensor, etc. Must list more than 4 components.

A hockey puck slides on the ice with an initial velocity of vi1 = 5 m/s in the positive x direction. A second hockey puck is sliding to the left with an initial velocity of vi2 = 3 m/s. The two pucks collide and after the collision puck 1 has a final velocity of vf1 = 3 m/s in the positive x direction at an angle of 30 degrees above the positive x axis. Is the collision elastic or inelastic?

Please show all work.

19.

How is the probability of something defined in terms of microstates and macrostates?

An object is moving along a straight line, and the uncertainty in its position is 2.20 m. (a) Find the minimum uncertainty in the momentum of the object. Find the minimum uncertainty in the object's velocity, assuming that the object is (b) a golf ball (mass = 0.0450 kg) and (c) an electron.

Two rods, one made of brass and the other made of copper, are joined end to end. The length of the brass section is 0.500 m and the length of the copper section is 0.700 m . Each segment has cross-sectional area 0.00700 m2 . The free end of the brass segment is in boiling water and the free end of the copper segment is in an ice-water mixture, in both cases under normal atmospheric pressure. The sides of the rods are insulated so there is no heat loss to the surroundings.

A. What is the temperature of the point where the brass and copper segments are joined?

B.

What mass of ice is melted in 9.00 min by the heat conducted by the composite rod? Express your answer with the appropriate units.

If you were to replace the ocean with or mercury or oil, which works best for a boat's ability to float?. Thank you.

A 6.0 kg freshwater fish at the surface of a lake is neutrally buoyant.If the density of its body with its swim bladder deflated is 1060 kg/m3, what volume of gas must be in the swim bladder for the fish to be neutrally buoyant? Express your answer to two significant figures and include the appropriate units.