Answer:
Light of a shorter wavelength should be used. 
Explanation:
This is studied in the phenomenon called photoelectric effect, in which light is able to release electrons from a metal, said electrons are called photoelectrons .
The experiments that have been carried out show that <u>increasing  or decreasing the intensity of the light will not cause the photoelectrons to be emitted</u>, what will cause the photoelectrons to be emitted is to increase the frequency of the incident light.
And a higher frequency corresponds to a shorter wavelength according to the equation:

(where  is frequency,
 is frequency,  the speed of light, and
 the speed of light, and  the wavelength)
 the wavelength)
So the answer is that the wavelength of the light must be shortened to cause the emission of electrones.
 
        
             
        
        
        
Answer:
a) The velocity is 2.94m/s
b) 0.441
Explanation:
a) Assume gravity is 9.8m/s^2
Use the equation below to solve for the velocity at 0.30 seconds
 ,
, 
vf =unknown velocity  vi= initial velocity vi=0m/s  a= 9.8m/s^2 t=0.30seconds
Step 1: Substitute the variables with the knowns

Step 2: Solve

b) 
Use the equation below to solve for the displacement at 0.30 seconds

Step 1: Substitute the same variables with the knowns

Note that vi*t=0 as vi=0m/s
Step 2: Solve
x=0.441m
 
        
             
        
        
        
Answer:
Try a Cold Pack. Use a Heating Pad or Hot Compress. Ease Pressure on Your Scalp or Head. Dim the Lights. Try Not to Chew. Hydrate. Get Some Caffeine. Practice Relaxation.
 
        
                    
             
        
        
        
When I find a problem like this, I find it helpful to think about what I know and what equation will help me.
The question tells us the frequency of the wave 

 Hz. We want to work out the wavelength. What equation links these two quantities?
Wave Speed = Frequency x Wavelength
(we know all electromagnetic waves travel at the speed of light in a vacuum)

and then divide by 

 to get the wavelength.
Wavelength = 

 m<u />
 
        
        
        
Answer:
Air and ice
Explanation:
convection, process by which heat is transferred by movement of a heated fluid such as air or water. 
Everyday Examples of Convection:
radiator - A radiator puts warm air out at the top and draws in cooler air at the bottom. 
steaming cup of hot tea - The steam you see when drinking a cup of hot tea indicates that heat is being transferred into the air.
 ice melting - Ice melts because heat moves to the ice from the air.