Answer:
3.76 m/s
Explanation:
Instantaneous velocity: This can be defined as the velocity of an object in a non uniform motion. The S.I unit is m/s.
v' = dx(t)/dt..................... Equation 1
Where v' = instantaneous velocity, x = distance, t = time.
Given the expression,
x(t) = 28.0 m + (12.4 m/s)t - (0.0450 m/s³)t³
x(t) = 28 + 12.4t - 0.0450t³
Differentiating x(t) with respect to t.
dx(t)/dt = 12.4 - 0.135t²
dx(t)/dt = 12.4 - 0.135t²
When t = 8.00 s.
dx(t)/dt = 12.4 - 0.135(8)²
dx(t)/dt = 12.4 - 8.64
dx(t)/dt = 3.76 m/s.
Therefore,
v' = 3.76 m/s.
Hence, the instantaneous velocity = 3.76 m/s
 
        
             
        
        
        
The centripetal force acts upon an object moving in a circle at constant speed.  The centripetal force acts perpendicular to the direction of motion , the speed of object will remain constant.
 
        
             
        
        
        
Yo sup??
we should know that 
work done=force*displacement
W=F.s
F=10 N
s=8 m
therefore
W=10*8
=80 N
Hope this helps.
 
        
             
        
        
        
Answer:
(a). Index of refraction are  = 1.344 &
 = 1.344 &  = 1.406
 = 1.406
(b). The velocity of red light in the glass  2.23 ×
 2.23 ×
The velocity of violet light in the glass  2.13 ×
2.13 ×
Explanation:
We know that 
Law of reflection is 

Here 
 = angle of incidence
 = angle of incidence 
  = angle of refraction
 = angle of refraction 
(a). For red light
1 ×  =
 =  ×
 × 
 = 1.344
 = 1.344
For violet light
1 ×  =
 =  ×
 × 
 = 1.406
 = 1.406
(b). Index of refraction is given by

 = 1.344
 = 1.344


 2.23 ×
 2.23 ×
This is the velocity of red light in the glass.
The velocity of violet light in the glass is given by

 2.13 ×
2.13 ×
This is the velocity of violet light in the glass.