Section+2+chap+4

=Section 2- Accidents= toc

Physics Talk
page 363 4/28/11

gravitational potential energy: the energy a body possess as a result of its position in a gravitational field kinetic energy: the energy an object possesses because of its speed joule: the SI unit for all forms of energy; equivalent units for the mechanical energy: the sum of kinetic energy and potential energy

Checking Up
page 367 4/28/11

1. if the incline was steeper the ball will roll faster 2. If the mass increases then the height decreases and if the heigh increases then the mass increases 3. if the speed increases the mass decreases and if the mass increases then then speed deacreases 4. The GPE decreases because the height is decreasing 5. 30,000 J

Physics To Go
page 370 4/28/11

1. B 2. It starts off with KE which is 1/2mv^2 and then when it goes up hills it transfers to GPE which is 1/2mv^2 3. GPE= 60,000 KE= 50,000 both= 11,000 GPE= 0 Ke= 0 both = 0 GPE= 30,000 KE=750 both = 30,750 GPE= 15,000 KE= 150,000 both= 165,000 5. GPE = 75,000 KE = 500,000 both 575,000 GPE= 0 KE= 0 both= 0 GPE = 37500 KE= 375,000 both= 412500 GPE= 15,000 KE 150,000 both= 165,000 7a. GPE=mgh=(.2kg)(10m/s)(.75)=2.45 J 7c. half way to the bottom 8. no, the mass cancels out in the conservation of energy 9a. B 9b. C and F 9c. D


 * Trial || Mass (kg) || Height (m) || Gpe Top || Width of ball(m) || time through gate || V at bottome || KE at bottom || Percent Difference ||
 * 1 || .226 || .063 || .140 || .038 || .0369 || 1.03 || .113 || -15 ||
 * 2 || .226 || .147 || .326 || .038 || .0253 || 1.50 || .254 || -20.9 ||
 * 3 || .226 || .229 || .507 || .038 || .0201 || 1.89 || .404 || -20.3 ||
 * 4 || .226 || .312 || .691 || .038 || .0172 || 2.21 || .551 || -20.1 ||
 * 5 || .226 || .397 || .879 || .038 || .0154 || 2.47 || .688 || -21.6 ||