If the blocks are released from rest, how long does it take the 4.0 kg
k
g
block to reach the floor?

The gravitational potential energy is converted to kinetic energy hence the time taken to fall is 0.45 seconds
We must note that as the block falls, graviataional potential energy is converted to kinetic energy hence;
mgh = 1/2mv^2
gh =0.5v^2
v = √gh/0.5
v = √9.8 * 1/0.5
v = 4.4 ms-1
Now;
v = u + gt
Since the blocks are dropped from a height, u =0 m/s
4.4 = 9.8 * t
t = 4.4/9.8
t = 0.45 seconds
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