Answer:
D
Explanation:
The rubber rod having been rubbed with fur get a net negative charge thereby gaining more mass which means the mass has increased compared to before it was rubbed against the fur while the glass rod having been rubbed with the silk to give it a net positive has lost mass and therefore has less mass compared to before it was rubbed on the silk.
The fundamental frequency of a string is given by:

where L is the string's length, T the tension and

the linear density of the string.
We can see that f1 is proportional to the square root of T:

.
This means that if the new tension is half the initial value, the new fundamental frequency will be proportional to

So, the new fundamental frequency will be
The reason the efficiency is always less than 100% is because there is always some sort of friction in the machine.
Answer: because of friction
Answer:
Decreases
Explanation:
Force= mass * acceleration
If the mass increases but force stays the same then the acceleration would have to decrease to maintain the same force
No voltage, no current. The battery provides potential difference(v) to the circuit. In case of no potential difference, theres no current.