1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

GCSE Physics : Temperature & Gravitational potential energy

  1. Jun 3, 2017 #1
    1. The problem statement, all variables and given/known data
    Q7. Some lead shot with a mass of 50 grams is placed into a card board box the distance from one end to the other being 1m. The ends are sealed with rubber bungs in order to prevent the lead shots from falling out, the tube is rotated so the lead shots fall down from one end to hit the rubber bung at the opposite end.

    A) A student rotates the tube 50 times. Calculate the total decrease in the gravitational potential energy store of the lead shot in the process.

    B) The Specific Heat Capacity of the lead shots is 160J/kg°c . Calculate the rise in temperature after the tube has been rotated 50 times.

    C) Why is the temperature rise of the lead shot likely to be less than what was calculated in part B.

    2. Relevant equations

    Gravitational potential energy = mass x gravitational field strength x height
    Change in temperature= Change in energy / mass x specific heat capacity
    Final GPE - Initial GPE

    3. The attempt at a solution

    Question A ) Firstly, I had calculated the initial GPE of the lead shots which I had derived to be 0.5J ( Note: The value 10 was used for gravitational field strength) as I had done GPE = 0.05kg x 10N/M x 1m. As for the second value because it was said to be flipped 50 times I had multiplied the height by 50, this meant that I did GPE= 0.05kg x 10N/M x 50 = 25J . Assuming the second set of values is the final GPE I did 25J - 0.5J= 24.5J lost

    As for the other two questions I could not think of anything.
  2. jcsd
  3. Jun 3, 2017 #2


    User Avatar
    Gold Member

    A) If we turn it 50 times, that is an even number, so maybe I would expect GPE at the end to be the same as at the start?
    B) The second equation has everything you need to work out the temp rise when 25J of energy is given to the lead. You know mass and SHC.
  4. Jun 4, 2017 #3


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    It is unclear whether a rotation is 180 degrees or 360.
    Judging from this:
    it probably means 180.
    This is not clear either. As tech99 points out, the net change in GPE is zero. But you are almost surely right to interpret this as being the sum of all the GPEs lost in each rotation.

    What second set of values? Why subtract one rotation?
    What happened to all that lost GPE?
    Since the shot moves to the end each (half) rotation, it makes no difference whether it is odd or even.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Threads - GCSE Physics Temperature Date
British Physics Olympiad 2004 (GCSE) Mar 6, 2015
GCSE Additional physics - NEED HELP =D Jun 10, 2008
GCSE physics problem Feb 5, 2007
A GCSE Physics Question from the UK Dec 14, 2006
Gcse PHysics coursework practical help Dec 2, 2003