Answer:
A. Distance over which the force is applied
Explanation:
As we know that in pulley system the mass of the car is balanced by the tension in the string
so here we will have

so here in order to decrease the force needed to lift the car we have to increase Distance over which the force is applied
So here if we increase the distance over which force is applied then it will reduce the effort applied by us in this pulley system as the torque will be more if the distance is more.
 
        
             
        
        
        
Answer:

Explanation:
given,
weight of swimmer = 510 N
length of ledge, L = 1.75 m
vertical height of the cliff, h =  9 m
speed of the swimmer = ?
horizontal velocity  of the swimmer should be that much it can cross the wedge.
distance = speed x time
d = v_x × t
1.75 = v_x × t ........(1)
now,time taken by the swimmer to cover 9 m
initial vertical velocity of the swimmer is zero.
using equation of motion for time calculation


   t² = 1.938
   t = 1.39 s
same time will be taken to cover horizontal distance.
now, from equation 1
1.75 = v_x × 1.39

horizontal speed of the swimmer is equal to 1.26 m/s
 
        
             
        
        
        
Answer:
V_{average} =  ,     V_{average} = 2 V
  ,     V_{average} = 2 V
Explanation:
he average or effective voltage of a wave is the value of the wave in a period
 
             V_average = ∫ V dt
in this case the given volage is a square wave that can be described by the function
            V (t) = 
to substitute in the equation let us separate the into two pairs
              V_average = 
              V_average = 
              V_{average} = 
 
we evaluate  V₀ = 4 V
              V_{average} = 4 / 2)
              V_{average} = 2 V
 
        
             
        
        
        
There water has a lot of salt in it, so it would be denser. People float better when the water is denser.