# October 3, 2007 I have no voice today…

## Presentation on theme: "October 3, 2007 I have no voice today…"— Presentation transcript:

October 3, 2007 I have no voice today…
Hence, those dreadful slides, so that I do not need to speak much… or cancel the class… These slides are in the course web site, under Chapter 8.

A few reminders Assignment 4, due Wednesday, October 10, by 5 pm
Assignement 5 will be due, Friday, October 19 Today’s Office Hours: 1 – 4 pm

Assignment 4 P. 203 #66 Should be a straightforward application of the Kinetic-Energy Theorem, where you use W = Fd, and you look for F. P.203 #74 Use P = W/t and KE Theorem. P. 237 #64 similar to P. 236 #52, discussed later today. P.236 #38 similar to Example 8-10, discussed next.

Equation of the day

where

and

Potential Energy Defined for conservative force as
Example: Gravitational Force

P. 226, Example 8-10 A block of mass m1 = 2.4 kg is connected to a second block of mass m2 = 1.8 kg. When the blocks are released from rest, they move through a distance d = 0.5 m, at which point m2 hits the floor. Given that the coefficient of kinetic friction between m1 and m2 is mk = 0.45, find the speed of the blocks just before m2 lands.

P. 236, Problem 52 A 61-kg skier encounters a dip in the snow’s surface that had a circular cross section with a radius of curvature of 12 m. If the skier’s speed at point A in the Figure is 8.0 m/s, what is the normal force exerted vy the snow on the skier at point B? Ignore frictional forces.

P. 238, Problem 81 An ice cube is placed on top of an overturned spherical bowl of radius r as shown in the Figure. If the ice cube slides downward from rest at the top of the bowl, at what angle q does it separate from the bowl? In other words, at what angle does the normal force between the ice cube and the bowl go to zero?