, how is electrostatic force related to amount of charge?

What is the quantity which is measured by the area occupied below the velocity- time graph?

Aparticle is moving around in a circle and its position is given in polar coordinates as x = rcosθ, and y = rsinθ, where r is the radius of the circle, and θ is in radians. from these equations derive the equation for centripetal acceleration.

Two atoms with different mass number but the same atomic number are called a) elements. b) ions. c) isotopes. d) nuclei.