If the object, ends up with a positive charge, then it is missing electrons. if it is missing electrons, then it must have been removed form the object during the rubbing process.
Answer: buzzer.
The working principle of a buzzer is the conversion of electrical energy to sound energy.
The switch just cuts or permits the flow of current, the motor convertes electrical or other kind of energy into mechanical energy, a bulb converts electrical energy into light and a battery converts chemical energy into electrical energy.
Answer:

Solution:
As per the question:
Mass of first object, m = 120 kg
Mass of second object, m' = 420 kg
Mass of the third object, M = 69.0 kg
Distance between the m and m', d = 0.380 m
Now,
To calculate the gravitational force on the object of mass, M placed mid-way due to mass, m:
To calculate the gravitational force on the object of mass, M placed mid-way due to mass, m':
To calculate the gravitational force on the object of mass, M placed mid-way due to mass, m and m':


False, his first law states: An object that's in motion will remain in motion at a constant velocity unless it's acted on by an unbalanced force.