Answer:

Explanation:
As we know that average velocity is defined as the ratio of total displacement of the object and its time interval.
so here we can say

now we know that in one complete revolution the total displacement of the tip of the seconds hand is zero
because it will have same position after one complete revolution from where it starts
so here we can say that the average velocity will be zero

Answer:
Power factor of the AC series circuit is 
Explanation:
It is given that,
Impedance of the AC series circuit, Z = 60 ohms
Resistance of the AC series circuit, R = 30 ohms
We need to find the power factor of the circuit. It is given by :




So, the power factor of the ac series circuit is
. Hence, this is the required solution.