Answer:
very hard others will answer it
Explanation:
hard
 
        
             
        
        
        
A. The cliff was 30.7 m high
B. I also got 9.5 as the horizontal distance 
Here is my work, I find making charts like this one to find knowns and unknowns can be helpful
 
        
        
        
Answer:
8 time increase in K.E.
Explanation:
Consider Mass of truck = m kg and speed = v m/s then 
 K.E. = 1/2 ×mv²
If mass and speed both are doubled i.e let m₀ = 2m and v₀ = 2v then 
(K.E.)₀ =  1/2 ×2m(2v)² 
(K.E.)₀ = 8 (1/2 × mv²) = 8 × K.E.
 
        
             
        
        
        
It's (whatever number comes after 'hold') divided by 2.5 .