From the principle of conservation of linear momentum, the mass of Lee is 50 Kg.
Momentum is the product of mass and velocity. The principle of conservation of linear momentum states that the total momentum before collision is equal to the total momentum after collision.
Let the mass of Lee be m
Hence;
(4.0-kg × 3.0 m/s) + (m × 3.0 m/s) = (4.0-kg × 15.5 m/s) + (m × 2.0 m/s)
12 + 3m = 62 + 2m
12 - 62 = 2m - 3m
-50 = -m
m = 50 Kg
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