Lab 6 Work & Conservation of Energy
| | | | | | PHY250L
Pre-Lab |Questions
1. The | force | due | to | a | spring | is | variable | and | is | quantified | by | F | = | kx, | where | k | is | the
| spring |constant |and |x |is |the |displacement. |Given |the |graph |of |the |force |versus |displacement
| graph
for |a |spring |in |Figure |5, |write |an |equation |for |the |amount |of |work |done |by |the |spring.
Figure |5: |Force |versus |displacement |of |a |spring.
W=∫F= |1/2kx^2
2. Consider |the |ball |example |in |the |introduction |when |a |ball |is |dropped |from |3 |meters. |After |the
| ball |bounces, |it |raises |to |a |height |of |2 |meters. |The |mass |of |the |ball |is |0.5 |kg
a. What |is |the |speed |of |the |ball |right |before |the |bounce?
| V=√2gh |= |√2(9.8)(3)=7.668 |m/s
, Lab 6 Work & Conservation of Energy
| | | | | | PHY250L
b. How |much |energy |was |converted |into |heat |after |the |ball |bounced |off |the |ground?
| (Hint: |Thermal |Energy |(TE) |will |now |need |to |be |included |in |your |conservation |of
energy |equation |and |you |will |now |need |to |know |the |mass |of |the |ball)
|
TE=Mg(h1-h2)= |(0.5)(9.8)(3-2)=4.95J
c. What |is |the |speed |of |the |ball |immediately |after |the |ball |bounces |off |the |ground?
| V=√2gh |= |√2(9.8)(2)=6.261 |m/s
3. Both |kinetic |and |potential |energy |are |part |of |the |thrill |of |roller |coasters. |For |this |exercise, |you
| will |examine |the |path |of |a |roller |coaster |and |describe |what |type |of |energy |is |at |work. |Use
| Figure |6 |to |answer |the |following |questions:
Figure |6: |Different |points |in |a |roller |coaster’s |motion.
a. Describe |the |kinetic |and |potential |energy |at |each |point |of |the |roller |coaster |path.
At |point |A, |the |potential |energy |is |the |highest |and |the |kinetic |energy |is |the |lowest. |At
| point |B |and |point |F, |the |potential |energy |is |0, |but |there |is |the |maximum |kinetic
| energy. |At |point |C, |there |is |high |potential |energy, |but |low |kinetic |energy. |Point |D |has
| low |potential |energy |(but |not |as |low |as |points |b |and |f) |and |high |kinetic |energy. |Point
| E |is |just |middle |potential |and |kinetic |energy.
| | | | | | PHY250L
Pre-Lab |Questions
1. The | force | due | to | a | spring | is | variable | and | is | quantified | by | F | = | kx, | where | k | is | the
| spring |constant |and |x |is |the |displacement. |Given |the |graph |of |the |force |versus |displacement
| graph
for |a |spring |in |Figure |5, |write |an |equation |for |the |amount |of |work |done |by |the |spring.
Figure |5: |Force |versus |displacement |of |a |spring.
W=∫F= |1/2kx^2
2. Consider |the |ball |example |in |the |introduction |when |a |ball |is |dropped |from |3 |meters. |After |the
| ball |bounces, |it |raises |to |a |height |of |2 |meters. |The |mass |of |the |ball |is |0.5 |kg
a. What |is |the |speed |of |the |ball |right |before |the |bounce?
| V=√2gh |= |√2(9.8)(3)=7.668 |m/s
, Lab 6 Work & Conservation of Energy
| | | | | | PHY250L
b. How |much |energy |was |converted |into |heat |after |the |ball |bounced |off |the |ground?
| (Hint: |Thermal |Energy |(TE) |will |now |need |to |be |included |in |your |conservation |of
energy |equation |and |you |will |now |need |to |know |the |mass |of |the |ball)
|
TE=Mg(h1-h2)= |(0.5)(9.8)(3-2)=4.95J
c. What |is |the |speed |of |the |ball |immediately |after |the |ball |bounces |off |the |ground?
| V=√2gh |= |√2(9.8)(2)=6.261 |m/s
3. Both |kinetic |and |potential |energy |are |part |of |the |thrill |of |roller |coasters. |For |this |exercise, |you
| will |examine |the |path |of |a |roller |coaster |and |describe |what |type |of |energy |is |at |work. |Use
| Figure |6 |to |answer |the |following |questions:
Figure |6: |Different |points |in |a |roller |coaster’s |motion.
a. Describe |the |kinetic |and |potential |energy |at |each |point |of |the |roller |coaster |path.
At |point |A, |the |potential |energy |is |the |highest |and |the |kinetic |energy |is |the |lowest. |At
| point |B |and |point |F, |the |potential |energy |is |0, |but |there |is |the |maximum |kinetic
| energy. |At |point |C, |there |is |high |potential |energy, |but |low |kinetic |energy. |Point |D |has
| low |potential |energy |(but |not |as |low |as |points |b |and |f) |and |high |kinetic |energy. |Point
| E |is |just |middle |potential |and |kinetic |energy.
