the radius of a curvature

the radius of curvature of a spherical mirror is 32 cm. rays parallel to the axis of the mirror will be brought into focus at a point that is what distance fron the mirror? a. 8.0cm b. 32 cm c. 4.0 cm d. 16cm

a car traveling

a car traveling at 20m/s is brought to a halt by applying the brakes in 4s. what is the magnitude of acceleration of the car a. 2m/s^2 b. 3m/s^2 c. 5m/s^2 d. 4m/s^2

the coefficent

the coefficent of thermal conductivity has the unit a. j/(mk) b. w/(mk) c. j(sk) d.w/(sk)

a tranverse traveling

a tranverse traveling wave is described by the equation y(x,t) = 10 sin(8 pie + pieT), where x and y are in meters and t in seconds. the wavelength and freaquency of the wave are a. .25m and .5 hz b. 4m and .5hz c. .25m and 2hz d. 4m and 2hz

A plane is 45 degrees, mass, acceleration, gravity.

Please Help. A plane is 45 degrees to the horizontal with a stationary mass on it. The mass is 12 kg and the acceleration of gravity is 9.8 m/s^2. What is the magnitude of the force of friction required to keep the mass from moving? Answer with the number of Newtons using digits. Thanks.

relativistic momentum

Hi. Can someone please show me how to do the following problem? Thank you. "A football player with a mass of 88 kg and a speed of 2.0 m/s collides head-on with a player from the opposing team whose mass is 120 kg. The players stick together and are at rest after the collision. Find the speed of the second player, assuming the ...continues

time dilation

Hi. I'm confused about the following problem: "The radar antenna on a navy ship rotates with an angular speed of 0.22 rad/s. What is the angular speed of the antenna as measured by an observer moving away from the antenna wth a speed of 0.62c?" It seems to me that 0.22 rad/s is the proper time, the delta t0, rather than th ...continues

photons

Hi. Can someone please show me how to do the following problem? Thank you. "An AM radio station operating at a frequency of 970 KHz radiates 250 kW of power from its antenna. How many photons are emitted by the antenna every second?" The answer is 3.9 x 10^32, but I'm not sure how to get there.

photoelectric effect

"The work function of gold is 4.58 eV. What frequency of light must be used to eject electrons from a gold surface with a maximum kinetic energy of 6.48e-19?" Here's what I did: W0 = (4.58 eV) (1.6e-19) = 7.33e-19 J Kmax = hf - W0 so f = (Kmax / h) + W0 f = (6.48e-19 / 6.626e-34) + 7.33e-19 = 9.78e14 Hz But that's ...continues

Period of Pendulum

The period T (in seconds) of a simple pendulum is a function of its length l (in feet), given by T(l)=2pie sqrt 1/g Express the length l as a function of the period T.