Answer:
v = -0.45 m/s
Explanation:
Assuming the canoe was initially at rest with momentum L = 0
and that the dog's velocity is in the positive direction
conservation of momentum
0 = 15(1.2) + 40v
v = -0.45 m/s
The scientist who discovered the two elements radium and polonium would be Marie Curie in 1898.
Hope this helps!