One should check the battery every week.
A battery if not maintained properly can cause it to die earlier or get damaged. The reasons why should the battery be checked regularly is that due to improper management of the battery and also the weather conditions, the battery usually gets corroded easily and the battery won't be able to work properly.
The connections must be checked properly so that the battery gets charged properly and should not die while driving.
 
        
                    
             
        
        
        
C. 2000 calories.
Explanation/calculation:
Specific heat capacity = calories / mass * (final temperature - initial temperature)
1 = calories / 100 * (60 - 40)
1 = calories / 100 * 20
1 * (100 * 20) = calories
1 * 2000 = calories
2000 = calories
        
                    
             
        
        
        
Answer:
 4.16m/s²
Explanation:
According to Newtons second law;

Fm is the moving force
 is  the coefficient of kinetic friction between the child and the slide
 is  the coefficient of kinetic friction between the child and the slide
m is the mass 
g is the acceleration due to gravity
a is the acceleration of the child
Substitute the given values and get the acceleration as shown;
35(9.8)sin27.5 - 0.415(35)(cos27.5) = 35a
158.38-12.88 = 35a
145.49 = 35a
a = 145.49/35
a = 4.16m/s²
Hence the acceleration of the body is  4.16m/s²
 
        
             
        
        
        
Answer:
= 9.8° 
Explanation:
Width of one slit (a₁ ) = 1 / 1000 mm=0.001 mm = 10⁻⁶ m.
width of one slit in case 2 (a₂ ) = 1/500 =2 x 10⁻⁶ m
angular position of fringe, Sinθ  = n λ /a
n is order of fringe , λ is wave length of light and a  is slit aperture
So Sinθ  ∝ 1 / a
Sin θ₁ /Sin θ₂ = a₂/a₁ ;
Sin20°/sinθ₂ = 2 / 1
sinθ₂ = Sin 20° / 2 = .342/2 = .171
θ₂ = 9.8 ° 
 
        
             
        
        
        
Answer:
 reflection is the act of reflecting or the state of being reflected while echo is
 reflection of sound waves from a surface back to the initial listener