Question

Problems from the textbook chapter 21: 3, 32. S3, 74. 83 are for your practice Your solutions of following problems are due by the end of Friday February 5^th class. A small metal ball with a mass of m_0 and a charge of q_0(q_0>0) is located in a region of space with an electric field of E_0(E_0>0) in +x direction. The ball is then released from rest at a distance of 3d above the ground (it will start to fall due to the gravity). What is the velocity of the ball after it has moved a vertical distance of d'? What is the kinetic energy of the ball when it hits the ground?

Answer 1

There will be acceleration of mass in both directions in x direction due to charge and electric field i.e. qE/m, and in vertical downward discretion due to gravity i.e. g.

Hence time to decend distance d is √2d/g. Hence velocity after that time will be qE×√2d/g/m in positive x direction and √2gd in downward vertical direction.

Kinetic energy will be 1/2 mv2. Hence (3gd + 3dq2E2/mg).