Final answer:
The speed of the two sleds after the collision is determined by using the conservation of momentum. Since the total initial momentum must equal the total final momentum, and the mass of the sleds has doubled, the final speed is half the initial speed, which is 2.8 m/s.
Step-by-step explanation:
The question involves a collision between two identical sleds, which is a classic conservation of momentum problem in physics. Since the sleds are identical and the collision results in the sleds sticking together, we can apply the principle of conservation of momentum to find the speed of the two sleds after the collision. We set the initial momentum (mass × velocity) equal to the final momentum, considering that the mass of the system doubles after the collision but the initial and final momenta must be equal.
Let m represent the mass of one sled, and v represent the initial speed of the moving sled. The initial momentum of the system is m × v (just the moving sled) since the other is stationary. After the collision, the combined mass is 2m, and we'll call the final velocity V of both sleds together.
Applying conservation of momentum:
m × v + m × 0 = (2m) × V
This simplifies to v = 2V, where v is the initial speed of the moving sled (5.6 m/s). Solving for V gives us V = v/2, which is 2.8 m/s. So, the correct answer is b) 2.8 m/s.