Answer:
348.57 kg
Explanation:
From the law of conservation of momentum,
Total momentum before the small child was picked = Total momentum after the small child was picked
mu + m'u' = V(m+m')................... Equation 1
Where m = mass of the skater, u = initial velocity of the skater, m' = mass of the small child, u' = initial velocity of the small child, V = common velocity after the child was picked.
Note: Assuming the small child was stationary before he was picked, the u' = 0 m/s.
making m' the subject of the equation
m' = (mu-mV)/V........................... Equation 2
Given: m = 80 kg, u = 6 m/s, V = 1.12 m/s.
Substitute into equation 2
m' = [(80×6)-(80×1.12)]/1.12
m' = (480-89.6)/1.12
m' = 390.4/1.12
m' = 348.57 kg.
Thus the mass of the small child = 348.57 kg
