11-7-08

TPJ November 7, 2008

First thing we did as you walked into class was pick up the packet “Mass vs. Weight Lab” pages 12-15, in unit four, Newton’s Second Law.

Daily Question’s:

1. When your car moves along the highway at constant velocity, the net force on it is zero. Why then, do you need to keep running your engine?

The answer is you would need to keep running your engine is because the car will continue to slow down cause of friction. So to keep the force and acceleration to equal out to have a constant velocity of zero you have to keep running the engine.

2. You push on a crate that sits on a smooth floor and it accelerates. If you apply four times the net force, how much greater will be the acceleration?

The answer would be four times greater because of linear relationship between pulling force, mass, and acceleration.

The first thing we did after going over the daily question was taking a look at the packet we got on 11/6/08; “Newton’s 2nd Law Applications” pages 7-11. We started off looking at page 8, read threw the directions and went over how to do problem 5.

Problem 5: Write both ways of ∑F to help find the solution.

First thing you would do is take the mass (5kg) then times that by the acceleration (0m/s/s) then do the math to see what it equals. Then you have your first equation. 1. ∑F = ma = 5kg * 0m/s/s = 0N Then in order to get the second equation you need to take all the force that you know and add them together and if you don’t know one let it as it is. 2. ∑F = F1 + F2 + F3 = 10N + 20N + F3 After finding both equations, since both the equations are equal to ∑F take the first equation and have it as equal to the second equation. 0N = 10N + 20N + F3 -30N = F3 Problem 5’s final picture should look like this.

Then we finished that rest of the packet and started working on the “Mass vs. Weight Lab” pages 12-15.

Assignments: No Homework But don’t forget you have a Unit Four Study Guide Packet

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