a) The student's speed after jumping is 1.07 m/s
b) The final speed of the laser is 10.4 m/s
Explanation:
a)
This issue can be approached through the momentum conservation principle: In the absence of external forces, the combined momentum of the student and the laser must remain unchanged. Hence, we can express:

where:
The initial momentum is zero
m = 42 kg signifies the mass of the laser
v = 1.5 m/s is the laser's final velocity
M = 59 kg is the mass of the student
V denotes the student's final velocity
Solving this for V, we can determine the student's speed:

Thus, the student's final speed calculates to 1.07 m/s.
b)
Here, both the laser and the student have a combined speed of 3.1 m/s prior to the student's jump; thus, the initial momentum isn't zero.
<pSo, we formulate the equation of momentum conservation as:

where:
m = 42 kg denotes the mass of the laser
M = 59 kg is the student’s mass
u = 3.1 m/s is their starting velocity
V = -2.1 m/s indicates the student's speed post-jump (she jumps backward)
v signifies the laser's final speed
When we resolve for v, we have:

Learn more about momentum: