Answer:
4 m/s
Explanation:
From the law of conservation of momentum,
Total momentum before collision = Total momentum after collision.
But,
Total momentum before collision = 0 m/s ( Both are at the center of the ice rink before the push).
0 = mv+m'v'
Where m = mass of Jack, m' = mass of Jill, v = final speed of Jack, v' = final speed of Jill
-mv = m'v'.................. Equation 1
make v the subject of the equation
v = m'v'/-m................... Equation 2
Given: m = 50 kg, m' = 40 kg, v' = 5 m/s.
Substitute into equation 2
v = -40(5)/50
v = -200/50
v = -4 m/s
Note: The negative sign shows that Jack moves to the left with a speed of 4 m/s
Hence Jack's speed = 4 m/s
