Answer:
maybe it is the first one
Answer:
Part a)

Part B)

Part c)

Explanation:
Part a)
As we know that

so we will have





Part B)
Angular speed of the yo-yo

so we have


Part c)
Tangential acceleration is given as



Answer:
-0.4 m/s
Explanation:
According to the law of conservation of momentum, the total momentum of the bullet - rifle system must be conserved.
The total momentum before the shot is zero, since they are both at rest:

While the total momentum after the shot can be written as:

where
m = 10 g = 0.010 kg is the mass of the bullet
M = 5 kg is the mass of the rifle
v = 200 m/s is the velocity of the bullet
V is the recoil velocity of the rifle
Since the total momentum is conserved, we can write:

So

And solving for V, we find the recoil velocity:

and the negative sign indicates that the velocity is opposite to the bullet.
Scientist would check what other scientists have said before they come up with their own scientific question. That way they can record the results from the others and compare them with their own findings when they conduct their own experiments and record the findings.