Physics/Dr. Lankar                  Name: ________________ section: ______________: grade: _______      

3-4 segments of pipe insulation track - masking tape - one marble - supports to create hills (books chairs ..) pan balance

PROCEDURE - HOW DOES THE POSITION OF A ROLLER COASTER AFFECT A MARBLE's ENERGY ?

step1: - Tape the 3 or 4 tracks segments together to create one 5-7m roller coaster track.
           - Tape one end of the track on a wall and tape the other end on the floor
            - Bend the track to create 2 full hills. Make the first hill taller than the second.



step2: Did the marble make it over both hills ? ______________________
If you say no, explain why it did not make it over the hills and describe how you could correct the track ?
_______________________________________________________________________________________

step3: Once your marble can make it over the 2 hills, measure and record the height of the marble's starting position on the track.
This is position #1. H = ____________cm. Also, use a pan balance to measure the mass of the marble in grams. m= _________g.
Record the data in the TABLE below.

step4: Use the same marble. For position #2,Find another starting point on the track where the marble only makes it over the first hill
and just comes close to going over the second hill. record this new starting height measurement in the TABLE. (position #2)

step5: For position #3, find another starting position on the track where the marble comes close to making it over the first hill, but does
not go over it. record this new starting height measurement in position #3 row of the data table.
TABLE:

step6: use a more massive marble and see the differences with the 3 positions.

ANALYSIS

1) Use the formula PE = mgh to compute the potential energy. To convert. Use cm  , grams and second.
You get another unit of energy called ergs. It is a smaller unit than joules.

2) Where did the marble have the most potential energy ?

3) at what point on the coaster does the marble have the greatest kinetic energy ?

4) How does the starting position of the marble affect the speed of the marble at the bottom of the first hill ?

5) What happens to the marble 's energy as it goes up and slows down ?

6) Would using a different marble affect the potential energy at the start ? (refer to step6)

GOING FURTHER

1) An arrow (m= 0.005 kg) is fired vertically from a height of ho= 5m above the ground and reaches the height of h = 51m
Ignoring air resistance, determine (A) the speed Vo with which the arrow was fired (B) The speed of the arrow has
after falling back to a height of h=20m above the ground.

hint: use conservation of energy.   the energy transfers from kinetic KE (when ho = 5m, speed = Vo)  to potential PE (when h=51m but speed=0) to
both kinetic and potential PE + KE (h=20m and speed = V). USe Energy = PE + KE  = constant  with  KE = 0.5 m V² and PE = mg (h - ho)

THat is KE1 = PE2 = KE3 + PE 3

2) using again the conservation of energy (KE + PE = constant, solve the following problem)

A motorcycle rider ti trying to leap across the canyon shown above by driving horizontally off the cliff.
When it leaves the cliff, the cycle has a speed of 55m/s . Ignoring air resistance, find the speed with which
the cycle strikes the ground on the other side.
hint use: PE + KE = constant so mgho + 0.5mVo² = mgh + 0.5 mV²

3) A 2kg rock is released from rest at a height of 20m . Ignore air resistance and determine
he kinetic energy, gravitational potential energy , and total mechanical energy at each of the heights indicated below:

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