Physics 42 HW Solutions Chapter 25

Problems: 9, 12, 23, 33, 36, 40, 47, 51, 54, 55, 65, 66, 72

9. An insulating rod having linear charge density λ = 40.0 μC/m and linear mass density μ = 0.100 kg/m is released from rest in a uniform electric field E = 100 V/m directed perpendicular to the rod (a) Determine the speed of the rod after it has traveled 2.00 m. (b) What If? How does your answer to part (a) change if the electric field is not perpendicular to the rod? Explain.

25.40 This is very similar to the problem in chapter 23, #35. The teacher solution manual gives a bad answer. You need to integrate with

( / )dq ds R dV Rk R d kd kλ λ θ λ θ λ θ λ θ= = → = → ∫ = ∆ .

Evaluating from / 2 3 / 2π π→ gives ( / )V k Q L kλ π π= =

c) Use conservation of momentum and energy and solve simulateously to find.

d) Solving for the velocity of m1 gives.