Let theta denote the angular displacement of a simple pendulum oscillating in a vertical plane. if the mass of the bob is m, then the tension in string is

So the tension  in the string T =mg cosθ

Explanation:

Now given that

mass of bob = m

Angle from vertical plane =θ

Lets T is the tension in the string

From the diagram

Weight of bob have two component ,first one(mg cosθ) balance the tension in the string and other one(mg sinθ)  make the bob to move in the plane.

So the tension  in the string T =mg cosθ

a small object of mass 3.66 g and charge -17.6 µc is suspended motionless above the ground when immersed in a uniform electric field perpendicular to the ground. what are the magnitude and direction of the electric field?

prndulum needs thread, weight clock to time swings