True or false- Normally, all objects are electrically positively charged

To do work, this truck uses energy stored in chemical fuel and an electrical battery. how much total energy does this truck put out?

The 10-kg double wheel with radius of gyration of 125mm about o is connected to the spring of stiffness k = 600 n/m by a cord which is wrapped securely around the inner hub. if the wheel is released from rest on the incline with the spring stretched 225 mm, calculate the maximum velocity v of its center o during the ensuing motion. the wheel rolls without slipping

Explain why electric current cannot exist if a current doesn't have a voltage source.