Answer:
5.704kg.m/s toward the pitcher
Explanation:
Impulse (Ft)= change in momentum
Impulse= m(v-u)
m=0.155 kg  ,       v=18.4 m/s  , u=18.4m/s
impulse=0.155[-(18.4) - (18.4)]
         =  0.155(-36.8)
         = -5.704 kg.m/s
the negative means towards the pitcher
 
        
             
        
        
        
Answer:
sphere #1 carries positive charge and #2 carries negative charge
This is because from the laws of static electricity, disconnecting the copper wire makes #1 to be positively charged and #2 to be negatively charged
 
        
             
        
        
        
Answer:
correct answer is C
Explanation:
The photoelectric effect was correctly described by Einstein, where he assumes that the light ray is formed by photons that are articulated and behaves like an elastic shock, the energy of this particular is described by the Planck equation.
              K = h f + Ф
where k is the kinetic energy of the electrons, f the frequency of the photons and Ф the work function of the material.
In this experiment, red light removes electrons, it is assumed that each photon spreads an electron if we have another light with more energy and 10% more intense, that is, with 10% more shapes and each arcane an electron the number of electrons removed of; material is increased by 10%.
The change in wavelength and consequently the frequency
             c = λ f
             f = c /λ
therefore, the wavelength of the voilet λ = 400 num has a higher frequency and therefore more energy, so that the turned-on turns have more kinetic energy.
With these approaches we examine the final answers where the correct answer is C
 
        
             
        
        
        
Answer:
The doorbell transforms electrical energy into sound.
Explanation:
The doorbell MAY turn electrical energy into motion of a striker which then impacts a resonator creating sound. However all door bells do not have solenoids. Some are electronic playing recordings when activated. 
All doorbells do produce sound, though.