Answer:
Part 1)
Boat A will win the race
Part 2)
Boat A will win the race by 48 km as the 2nd boat will reach the other end while boat A will just touches the finish line
Part 3)
average velocity must be zero
Explanation:
As we know that the distance moved by the boat is given as

now the time taken by the boat to move to and fro is given as



Time taken by Boat B to cover the distance


Part 1)
Boat A will win the race
Part 2)
Boat A will win the race by 48 km as the 2nd boat will reach the other end while boat A will just touches the finish line
Part 3)
Since the displacement of Boat A is zero
so average velocity must be zero
 
        
             
        
        
        
Acceleration in m/s^2 = 2/10 = 0.2 m/s^2
        
             
        
        
        
Data:
KE (Kinetic Energy) = ? (Joule)
m (mass) = 1500 Kg 
v (speed) = 42 Km/h
converting to m/s (42 / 3.6), we have: v (speed) = 11.6 m/s
Formula:

Solving:




 
 
        
        
        
Answer:
143 °
Explanation:
a ) If d be the distance between slits , λ be wavelength of light used and at angle θ nth dark fringe is formed then 
d sinθ = ( 2n+1) λ/2
for first dark fringe 
d sinθ = λ/2
d /λ = 1/ 2 sinθ
1 / 2 sin15
= 1.93 
b ) 
For intensity of fringe at angle θ,  the relation is 
I = I₀ cos²θ
I / I₀  = cos²θ/2
Given I / I₀ =0. 1
0.1 = cos²θ/2
θ/2 = 71.5 
θ = 143 °
 
        
             
        
        
        
Assuming you're working in a 3D cartesian coordinate system, i.e. each point in space has an x, y, and z coordinate, you add up the forces' x/y/z components to find the resultant force.