Answer:
 
 
Explanation:
The tidal current flows to the east at 2.0 m/s and the speed of the kayaker is 3.0 m/s.
Let Vector  is the tidal current velocity as shown in the diagram.
 is the tidal current velocity as shown in the diagram.
In order to travel straight across the harbor, the vector addition of both the velocities (i.e the resultant velocity,  must be in the north direction.
 must be in the north direction. 
Let  is the speed of the kayaker having angle \theta measured north of east as shown in the figure.
 is the speed of the kayaker having angle \theta measured north of east as shown in the figure.
For the resultant velocity in the north direction, the tail of the vector  and head of the vector
 and head of the vector  must lie on the north-south line.
 must lie on the north-south line.
Now, for this condition, from the triangle OAB




Hence, the kayaker must paddle in the direction of  in the north of east direction.
  in the north of east direction.
 
        
             
        
        
        
<span>The tides on earth are caused mainly by earths gravitational interactions with the sun and the moon.</span>
        
             
        
        
        
Answer:
Resistivity ρ=1.12 x 10^-4 Ωm
Explanation:
ρ= RA/l, where R is resistance, A is cross sectional area and l is length
A=πr^2
Note Current is given R is proportion to temperature and inversely proportional to Current R=(20+273)/14*10^-2 =2000Ω
⇒ρ=R*πr^2/l all length in metre.
 
        
             
        
        
        
Answer:
Explanation:
Let initial extension in the spring= x₀
Force on the spring = F₀ 
Let spring constant = k 
Fo = k x₀
Fn = 3k x₀
Fn /Fo = 3
PEs0 ( ORIGINAL)  =1/2 k x₀²
PEsn ( NEW)  =1/2 k (3x₀)²
PEsn / PEs0 = 9