Physics 1 A, Section 6 October 16, 2008

Section Business • Quiz #1 was due 3 hours ago! • Homework and quiz solutions will be posted on-line on the course web page.

T. M. U. Problem 6. 4

T. M. U. Problem 6. 4 • Answer: Equal force; acceleration greater for bug

T. M. U. Problem 6. 1

T. M. U. Problem 6. 1 • Answer: Accelerate equally, and compare the force required.

T. M. U. Problem 6. 5

T. M. U. Problem 6. 5 • Answer: (a) and (b) are reaction pairs; (c) and (d) are not

T. M. U. Problem 6. 6

T. M. U. Problem 6. 6 accelerates to the left doesn’t accelerate

T. M. U. Problem 6. 3

T. M. U. Problem 6. 3 • Answer: Tension greatest between engine and front boxcar. Tension is 3 ma, 2 ma, ma from front to back.

Final Problem 9

Helpful hints • Free body diagrams – a good start. • Be consistent with signs. • massless strings – tension is constant along the free length • frictionless/massless pulleys – rope tension is constant over the pulley

Pulley

Pulley • Answer in more general case: tension T force T

Final Problem 9 • Answer: a) m 2/m 1 = 1 b) DD 1 = DD 2/2 c) a 2 = 2 g/9 d) v 2 = 2/3 sqrt(g. D), v 1 = 1/3 sqrt(g. D) e) decrease

Monday, October 20: • a gravity/circular orbit problem of some sort • Quiz Problem 37 • Optional, but helpful, to look at these in advance.

T. M. U. Problem 6. 2