Answer:
 (A) Speed will be 
(b) Change in kinetic energy =  
       
Explanation:
We have given mass of proton 
Acceleration of the proton 
Initial velocity u =  m/sec
 m/sec
Distance traveled by proton s = 3.90 cm = 0.039 m 
(a) From third equation of motion we know that 



(b) Initial kinetic energy 
Final kinetic energy 
So change in kinetic energy 
 
        
             
        
        
        
There is no acceleration of g in the x direction because the gravitational acceleration points downward. Also, on most studies we ignore the tidal forces since we are dealing with small bodies compared to the size of the earth.
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AS
 work done =W = F.d = F d cosФ     (Ф is angle between force F and displacement d) If a body/object is moving on a smooth surface (friction-less surface ) .There is no force acting on that body.  F=0 so W=FdcosФ= (0)dcosФ ⇒ W=0
Now if a body is facing some amount of force but under the action of force there is no displacement covered. d=0 so W =FdcosФ= F(0)cosФ ⇒W=0
example:  A person is applying a force on rigid wall but wall remains at rest there is no displacement occurs in wall.
The third term upon which work done  dependent is angle between force and displacement i.e Ф. If Ф=90° then W= FdcosФ= Fdcos90⇒ W=0   ( as cos 90°=0) 
 
        
             
        
        
        
Answer:
Power is the rate which work is done.
Explanation:
<em>Power</em> is the rate which work is done. Power is measured in watts.
<em>Work</em> is the use of force to move an object. Work is measured in joules
 
        
             
        
        
        
Because dark line spectra result from passing white light through ionized gasses and plasmas, which is what the atmosphere of stars are made of.  These frequencies are scattered by the star's atmosphere as it leaves the surface (photosphere) of the star, and don't make it to earth.