(a) how many electrons would have to be removed from a penny to leave it with a charge of +1.0×10−7 c? [4] (b) to what fraction of the electrons in the penny does this correspond? [6] [a penny has a mass of 3.11 g; assume it is made entirely of copper.]

Why don't you see your reflection in water with waves or repples

The period of a pendulum varies directly as the square root of the length of the pendulum and inversely as the square root of the acceleration due to gravity. find the period when the length is 144 cm and the acceleration due to gravity is 980 cm per second squared, if the period is 7pi seconds when the length is 289 cm and the acceleration due to gravity is 980 cm per second squared.

What pressure difference is required between the ends of a 2.0-m-long, 1.0-mm-diameter horizontal tube for 40 c water to flow through it at an average speed of 4.0 m/s?