Eoin

Light is incident of the surface of metallic sodium, whose work function is 2.3 eV. The maximum speed of the photoelectrons emitted by the surface is 2.90 × 106 m/s. What is the wavelength of the light?

Two parallel slits are illuminated by light composed of two wavelengths. One wavelength is λA = 572nm. The other wavelength is λB and is unknown. On a viewing screen, the light with wavelength λA = 572nm produces its third-order bright fringe at the same place where the light with wavelength λB produces its fourth dark fringe. The fringes are counted relative to the central or zeroth-order bright fringe. What is the unknown wavelength?

When a diverging lens is held 12.5 cm above a line of print, as in Figure below, the image is 7.2 cm beneath the lens. (a) Is the image real or virtual? (b) What is the focal length of the lens?

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A small mirror is attached to a vertical wall, and it hangs a distance of 1.54 m above the floor. The mirror is facing due east, and a ray of sunlight strikes the mirror early in the morning and then again later in the morning. The incident and reflected rays lie in a plane that is perpendicular to both the wall and the floor. Early in the morning, the reflected ray strikes the floor at a distance of 3.18 m from the base of the wall. Later on in the morning, the ray is observed to strike the floor at a distance of 1.25 m from the wall. The earth rotates at a rate of 15.0˚ per hour. How much time (in hours) has elapsed between the two observations?

The drawing shows two positive charges q1 and q2 fixed to a circle. At the center of the circle they produce a net electric field that is directed upward along the vertical axis. Determine the ratio q2/q1.

Figure: http://demo.webassign.net/ebooks/cj6demo/art/image...

The drawing shows two positive charges q1 and q2 fixed to a circle. At the center of the circle they produce a net electric field that is directed upward along the vertical axis. Determine the ratio q2/q1.

Figure: http://demo.webassign.net/ebooks/cj6demo/art/image...

In a vacuum, two particles have charges of q1 and q2, where q1 = +3.4UC. They are separated by a distance of 0.28 m, and particle 1 experiences an attractive force of 4.9 N. What is the value of q2, with its sign?

In a vacuum, two particles have charges of q1 and q2, where q1 = +3.4C. They are separated by a distance of 0.28 m, and particle 1 experiences an attractive force of 4.9 N. What is the value of q2, with its sign?

A steel section of the Alaskan pipeline had a length of 58.3 m and a temperature of 19.4 °C when it was installed. What is its change in length when the temperature drops to a frigid -39.8 °C?

A spring is attached to the bottom of an empty swimming pool, with the axis of the spring oriented vertically. An 7.10-kg hollow block of wood (ρ = 840 kg/m3) is fixed to the top of the spring and compresses it. Then the pool is filled with water, completely covering the block. The spring is now observed to be stretched twice as much as it had been compressed. Determine the percentage of the block's total volume that is hollow. Ignore any air in the hollow space.

A steel section of the Alaskan pipeline had a length of 58.3 m and a temperature of 19.4 °C when it was installed. What is its change in length when the temperature drops to a frigid -39.8 °C?

A square, 0.147 m on a side, is mounted so that it can rotate about an axis that passes through the center of the square. The axis is perpendicular to the plane of the square. A force of 17.8 N lies in this plane and is applied to the square. What is the magnitude of the maximum torque that such a force could produce?

John’s mass is 97.8 kg, and Barbara’s is 56.9 kg. He is standing on the x axis at xJ = +9.68 m, while she is standing on the x axis at xB = +2.96 m. They switch positions. How far and in which direction does their center of mass move as a result of the switch?

at 37.6 m/s. Going up a hill, the car s engine needs to produce 52.2 hp more power to sustain the constant velocity than it does going down the same hill. At what angle is the hill inclined above the horizontal? I m very stuck, any help appreciated.

A lake 1km square in area is reduced in depth by 5 mm in the space of 30 minutes through the process of evaporation. What is the latent heat flux (in W/m^2) associated with this evaporation. You may assume that the latent heat of evaporation is 2260kJ/kg and the density of water is 1000kg/m^3.

A student is trying to determine the half-life of radioactive iodine-131. He measures the amount,A , of iodine-131 in a sample solution every 8 hours. His data are shown in the table.

Time(h) = Amount(g)

0 = 5.33

8 = 5.16

16 = 5

24 = 4.83

32 = 4.74

40 = 4.6

48 = 4.48

(a) Find an appropriate exponential model of the data points.

Amount at time t, A(t) = ?

(b) Find the half-life of idoine-131 according to the exponential model in part (a).

Half-life, t = ?

Use the Laws of logarithms to rewrite the expression

log_3_(x^13 3√y^2)

in a form with no logarithm of a product, quotient or power.

After rewriting we have

log_3_(x^13 3√y^2) = A log_3_ + B log_3_y

With the constant A = ?

With the constant B = ?

Solve the following equation for t:

2.2 = 42(10)^t