Well, Velocity is the speed of something in a given direction, and speed is the rate at which someone or something is able to more or operate. They both invlove speed, so this is a hard one, but I wold say either B or D
Answer:
Explanation:
Given
mass of First Block 
Temperature 
mass of second block 
Temperature 
Heat capacity of aluminium c=899 J/kg-K
Final Temperature acquired by both blocks at steady state
Heat loss first block =Heat gain by second block




Initial velocity: 0
final velocity: 7 m/s
a = 3.6
t = ?
x = ?
(7-0)/3.6 = t
t = 1.94 s