What determines how many electrons will leave a piece of metal in the photoelectric effect

Ablock of mass m = 2.5 kg is attached to a spring with spring constant k = 710 n/m. it is initially at rest on an inclined plane that is at an angle of θ = 23° with respect to the horizontal, and the coefficient of kinetic friction between the block and the plane is μk = 0.19. in the initial position, where the spring is compressed by a distance of d = 0.16 m, the mass is at its lowest position and the spring is compressed the maximum amount. take the initial gravitational energy of the block as zero. a) what is the block's initial mechanical energy? b) if the spring pushes the block up the incline, what distance, l, in meters will the block travel before coming to rest? the spring remains attached to both the block and the fixed wall throughout its motion.

There are two routes similar in terrain; however, one route has an incline of approximately 28 degrees, and you must decide on which route to take. what is the maximum road grade that your fully loaded ecv can climb?

Clothes dryer uses about 7 amps of current from a 240 volt line. how much power does it use?