Answer:
leaf and a balloon is the correct answer
 
        
                    
             
        
        
        
Answer:
The cartilage is the structure that reduces friction between joints. 
Explanation:
Cartilage is the tissue between the bone joints. They are composed of several membranes and cellular groups. One of them called synovial membrane which provides lubricant to the edges of tissue that are touched by the bones. Reducing the friction and absorbing it so the body can move without obstacles. 
 
 
        
             
        
        
        
 it is just a matter of integration and using initial conditions since in general dv/dt = a it implies v = integral a dt 
v(t)_x = integral a_{x}(t) dt = alpha t^3/3 + c the integration constant c can be found out since we know v(t)_x at t =0 is v_{0x} so substitute this in the equation to get v(t)_x = alpha t^3 / 3 + v_{0x} 
similarly v(t)_y = integral a_{y}(t) dt = integral beta - gamma t dt = beta t - gamma t^2 / 2 + c this constant c use at t = 0 v(t)_y = v_{0y} v(t)_y = beta t - gamma t^2 / 2 + v_{0y} 
so the velocity vector as a function of time vec{v}(t) in terms of components as[ alpha t^3 / 3 + v_{0x} , beta t - gamma t^2 / 2 + v_{0y} ] 
similarly you should integrate to find position vector since dr/dt = v r = integral of v dt 
r(t)_x = alpha t^4 / 12 + + v_{0x}t + c let us assume the initial position vector is at origin so x and y initial position vector is zero and hence c = 0 in both cases 
r(t)_y = beta t^2/2 - gamma t^3/6 + v_{0y} t + c here c = 0 since it is at 0 when t = 0 we assume 
r(t)_vec = [ r(t)_x , r(t)_y ] = [ alpha t^4 / 12 + + v_{0x}t , beta t^2/2 - gamma t^3/6 + v_{0y} t ] 
        
             
        
        
        
Resistance ∞ (proportional) length 
resistance ∞ 1/ area
therefore, 
(the constant that we take is known as the resistivity)
resistance =  (resistivity*length )/ area
 resistivity = (resistance * area ) / length
                  = (3 * 45) / 3 =    135/3 = 45 Ωm
in short your answer is 45 Ωm
        
             
        
        
        
Given: Mass m = 400 Kg;   Height h = 3 m;     g = 10 m/s²
Required:  Work = ?
Formula: Work = Force x distance  F = ma    a = g    F = mg
W = fd
W = mgh
W = (400 Kg)(10 m/s²)( 3 m)
W = 12,000 Kg.m²/s²
W = 12,000 J