Physics - Unit 7 Test

• Pulley System on the test
• Ideal mechanic advantage by using diagram of pulleys
• PE + KE = PE’ + KE’ for the FRQ of the test
• Where did the energy go?
  • Sound, Heat, Friction, Deformation
• Work in
• Work out
• Potential Energy
• Kinetic Energy
• Which quantity is affected by friction: F${}_r$
• We don’t use machine to do less work
  • We do more work overtime
• Couple of questions from Penguin, Monkeys, Etc lab

Page O’ Notes §

• If a rock is thrown then it has a kinetic energy at the top
• KE = $\frac{1}{2}$m(v)${}^2$
• PE = mgh
• PE $\frac{1}{2}$k(x)${}^2$
  • k = spring constant
  • x = how much the spring has moved
• m${}_1$v${}_1$ + m${}_2$v${}_2$ = m${}_1$v${}_1$’ + m${}_2$v${}_2$’
  • Recall the bullet problem in the homework packet
• $△$ KE = KE${}_f$ - KE${}_i$
• KE${}_R$ = $\frac{1}{2}$(I)(W)${}^2$
• W = F(d) (Joules)
• W = F(d)(cos$\theta$)
• P = $\frac{work}{t}$ (watts)
• Conservation of energy equation:
• Momentum = mass x velocity
• AMA = MA = $\frac{F_r}{F_e}$
• IMA = F${}_r$d${}_r$ = F${}_e$d${}_e$ -> $\frac{F_r}{F_e}$ = **$\frac{d_e}{d_r}$
• efficiency = $\frac{MA}{IMA}$ * 100%
• solid ball vs hollow ball
  • solid gets down the hill first; smaller moment of inertia
  • hollow = rotational
  • solid = translational