Q1. A ball on a porch rolls 60 cm to the porch's edge, drops 40 cm, continues rolling on the grass, and ultimately stops 80 cm from the porch's edge.

Q2. 1) A ball of mass 1.020 g and positive charge q =45.2 microC is suspended on a string of negligible mass in a uniform electric field. We view that the ball hangs at an angle of theta=15.0 from the vertical. What is the magnitude of the electric field?

2) Two charges, Q1= 3.10 micro Coulombs, and Q2=6.70 micro Coulombs, are located at points (0,-3.50cm) and (0, +3.50cm).

What is the magnitude of the electric field at point P, located at (5.00cm, 0), due to Q1 alone?

What is the x-component of total electric field at P?

What is the y-component of total electric field at P?

What is the magnitude of total electric field at P?

Now let Q2=Q1= 3.10 micro Coulombs. Note that the problem now has a symmetry that you should exploit in your solution. What is the magnitude of the total electric field at P?

Given the symmetric situation of the previous problem, what is the magnitude of the force on an electron placed at point P?

3) An electron (mass m = 9.11×10-31kg) is accelerated in the uniform field E (E = 1.42×104N/C) between two parallel charged plates. The separation of the plates is 1.68cm. The electron is accelerated from rest near the negative plate and passes through a tiny hole in the positive plate. With what speed does it leave the hole?

4) Show that the gravitational force can be ignored by calculating the ratio of the gravitational to the electric force. Compute the ratio.