If the metal sphere on the Van de Graff has a charge of 0.14 Coulombs and the person has a mass of 62 kg, how much excess charge would the person need in order to levitate at a distance 25 cm from the center of the charged metal sphere if there is a distance 25 cm from the person to the sphere using Coulomb's Law to calculate the electrical force.      Give your answer as the number of Coulombs (with no unit label, as usual).

A balloon is rubbed on a sweater, giving the balloon a negative charge by adding an extra 3.9 x 107 electrons compared to its neutral state. What is the magnitude of the net charge on the balloon, in Coulombs?

A ping pong ball and a tennis ball are dropped and there is a very small gap between them when the tennis ball hits the floor. Indicate the directions of the momentums of the ping pong ball and the tennis ball after the tennis ball collides with the floor, but before the balls collide with each other. (Drawing a diagram may be helpful.)

Describe how the momentum of a single ball changes as it free falls from a height of approximately 1 m, collides with a hard floor, and rebounds.

If the answer is 2.8, -2.8 or -8.4, it is not CORRECT

Three blocks, light connecting ropes, and a light frictionless pulley comprise a system, as shown in the figure. An external force of magnitude P is applied downward on block A, causing block A to accelerate downward at a constant 2.5 m/s2. The tension in the rope connecting block B and block C is equal to 60 N. (a) What is the magnitude of the force P? (b) What is the mass of block C?

Current Attempt in Progress In the figure what is the net electric potential at point P due to the four particles if V = 0 at infinity, q = 2.12 fC, and d = 1.75 cm? d Number MI Units +q

Current Attempt in Progress In the figure what is the net electric potential at point P due to the four particles if V = 0 at infinity, q = 2.12 fC, and d = 1.75 cm? d Number MI Units +q

A 0.500 kg sphere moving with a velocity given by (2.00î – 2.60ĵ + 1.00k) m/s strikes another sphere of mass 1.50 kg moving with an initial velocity of (−1.00î + 2.00ĵ – 3.20k) m/s. (a) The velocity of the 0.500 kg sphere after the collision is (-0.90î + 3.00ĵ − 8.00k) m/s. Find the final velocity of the 1.50 kg sphere. R = m/s Identify the kind of collision (elastic, inelastic, or perfectly inelastic). ○ elastic O inelastic O perfectly inelastic (b) Now assume the velocity of the 0.500 kg sphere after the collision is (-0.250 + 0.850ĵ - 2.15k) m/s. Find the final velocity of the 1.50 kg sphere. ✓ = m/s Identify the kind of collision. O elastic O inelastic O perfectly inelastic (c) Take the velocity of the 0.500 kg sphere after the collision as (−1.00ỉ + 3.40] + ak) m/s. Find the value of a and the velocity of the 1.50 kg sphere after an elastic collision. (Two values of a are possible, a positive value and a negative value. Report each with their corresponding final velocities.) a…