Two charged particles placed at a separation of 20 cm exert 20 N of Coulomb force on each other. What will be the force if the separation is increased to 25 cm?

A body builder exerts a force of 150 N against a bullworker and compresses it by 20cm. Calculate the spring constant of the spring in the bullworker.

A satellite is projected vertically upwards from an earth station. At what height above the earth's surface will the force on the satellite due to the earth be reduced to half its value at the earth station? (Radius of the earth is 6400 km)

The force with which the earth attracts an object is called the weight of the object. Calculate the weight of the moon from the following data: The universal constant of gravitation G = 6.67 × 10^–11 N–m²/kg², mass of the moon = 7.36 × 10²² kg, mass of the earth = 6 × 10²⁴ kg and the distance between the earth and the moon = 3.8 × 10⁵ km.

Find the ratio of the magnitude of the electric force to the gravitational force acting between two protons.