The ball was moving for 0.8seconds
This is because 4/5 x 1 = 0.8
Hope this helps and good luckkkk :)
        
             
        
        
        
Answer:
A
Explanation:
All of the frictions are the same, but weight always goes straight down so it can only be A or B. Since they are going down a slope, then the normal force must be sloped. A is the only one out of A and B with a sloped normal force, so it has to be A
 
        
             
        
        
        
Answer:
time taken with speed 23 km/h will be 1.8 hours or 1 hour 48 minutes
Explanation:
Given:
Time is inversely proportional to the speed
mathematically,
t ∝ (1/r)
let the proportionality constant be 'k'
thus,
t = k/r
therefore, for case 1
time = 3 hr
speed = 14 km/hr
3 = k/14
also,
for case 2
let the time be = t
r = 23 km/h
thus, 
we have
t = k/23
on dividing equation 2 by 1
we get

or

or
t = 1.8 hr = or 1 hour 48 minutes ( 0.8 hours × 60 minutes/hour = 48 minutes)
 
        
             
        
        
        
Answer: sheet of charge 
Explanation:
a ) 
Since the charge is negative , potential will be negative near it . At a far point potential will be less negative. So potential will virtually increase on going away from the sheet . At infinity it will become almost zero. Electric field will be towards the plate , so potential will decrease towards the plate. 
b ) The shape of equi -potential surface will be plane parallel to the sheet of charge because electric field will be perpendicular to the sheet of charge and almost uniform near the sheet of charge.   The equi- potential surface is always perpendicular to electric field. 
C ) Electric field which is almost uniform near the sheet of charge is equal t the following 
E = σ / ε₀ where  σ is charge density of surface and  ε₀ is permittivity of medium whose value is 8.85 x 10⁻¹²
E = 3 x 10⁻⁹ / 8.85 x 10⁻¹² 
= .3389 x 10³
= 338.9 V / m 
spacing between 1 V 
= 1 / 338.9 m
= 2.95 X 10⁻3 m 
= 2.95 mm. 
 
        
             
        
        
        
Prior to determining the
experimental design, a scientist typically forms a hypothesis. The answer is
letter B. this is to prepare the scientist, the possible outcome of their
research before the experimental design whether they are wrong or not.