the purpose of fuses and circuit breakers is (first answer)
Answer:
Coefficient of friction.
Explanation:
The amount of friction divided by the weight of an object is equal to the coefficient of friction. It is a dimensional less number. It can be given by :

N is normal force.
= coefficient of friction

Answer:
The magnitude of momentum of the airplane is
.
Explanation:
Given that,
Mass of the airplane, m = 3400 kg
Speed of the airplane, v = 450 miles per hour
Since, 1 mile per hour = 0.44704 m/s
v = 201.16 m/s
We need to find the magnitude of momentum of the airplane. It is given by the product of mas and velocity such that,



or

So, the magnitude of momentum of the airplane is
. Hence, this is the required solution.
I believe the answer is the second one.