The answer is C. F=ma basically says that force is a function of mass multiplied by acceleration. The first two answers don’t make sense because there’s no necessary relationship between mass and acceleration. And for the last two, the higher the mass, the higher the force needed, therefore C is the correct answer.
        
             
        
        
        
<span>This is a true statement. Fitness is typically a long-term solution, not a short-term repair. When looking for fitness results, it will usually take weeks to months to see any tangible results, even though there could be some short-term benefits such as increased energy. This is why fitness is sometimes seen as a lifetime endeavor and not one that occurs overnight.</span>
        
             
        
        
        
Answer:
Photons.
Explanation:
Einstein explained the photoelectric effect by proposing that light is transmitted, not in the form of continuous waves, but in the form of many tiny, discrete packets of energy called photons. Photons are massless and  chargeless particle. The energy of a photon is given by :

f is the frequency of photon.                                                                  
 
        
             
        
        
        
Answer:
η = 2.57%
Explanation:
Given:
Output power of the steam power plant, P(out) = 200 MW
Consumption of coal, m = 700 tons/h = (700 × 10³)/3600 kg/s= 194.44 kg/s
Heating capacity of the coal, Cv = 40000 kJ/kg
now, 
Input power,  P(in) = mCv
or
P(in) =  194.44 kg/s × 40000 = 7777.77 MW
thus,
efficiency, η = P(out)/P(in) = (200 MW) / (7777.77 MW) = 0.02571
or
η = 2.57%