2019 PSLE Discussions and Strategies (Children born in 2007)
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AnxiousabtPSLE\" post_id=\"1938905\" time=\"1569902232\" user_id=\"180550:
Exactly!
But question 18 requires the energy conversion THE MOMENT it hits the ground....so CANNOT HAVE SOUND ENERGY because it is when the ball is bouncing back up . -
dottypooh\" post_id=\"1938909\" time=\"1569902362\" user_id=\"64091:
My DD also said the same. It's gravity. Cos only changing factor is the added weight. The rest are the same. Friction changes only when there is a change in surface.,ie, rougher or smoother.[/quote]Greater mass means more friction between floor and sofa. I think this is one of the trickier qns.
if DD rmember correctly, its not friction. its due to gravity..quixation\" post_id=\"1938899\" time=\"1569901776\" user_id=\"480:
[quote=whitecarrotcake post_id=1938888 time=1569900796 user_id=114080]
Friction between sofa and floor -
panickymum\" post_id=\"1938902\" time=\"1569901985\" user_id=\"64662:
Was that option 1? What option was it?
Potential to kinetic and sound energyhelpthismom\" post_id=\"1938898\" time=\"1569901397\" user_id=\"149507:
Anyone knows the answer for Q18 the rubber ball question about the energy conversion?
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panickymum\" post_id=\"1938902\" time=\"1569901985\" user_id=\"64662:
Was that option 1? What option was it?
Potential to kinetic and sound energyhelpthismom\" post_id=\"1938898\" time=\"1569901397\" user_id=\"149507:
Anyone knows the answer for Q18 the rubber ball question about the energy conversion?
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panickymum\" post_id=\"1938902\" time=\"1569901985\" user_id=\"64662:
Was that option 1? What option was it?
Potential to kinetic and sound energyhelpthismom\" post_id=\"1938898\" time=\"1569901397\" user_id=\"149507:
Anyone knows the answer for Q18 the rubber ball question about the energy conversion?
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AnxiousabtPSLE\" post_id=\"1938907\" time=\"1569902316\" user_id=\"180550:
I thought the moment any ball hits the ground, sound is produced. Plus, in the question, they stated that the ball bounced to a lower height. This is because some of its Kinetic Energy is lost as heat and sound energy, so i think the answer has to be KE - -> SE + GPE
So Q18 should be just potential to kinetic
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Was there a potential—>kinetic + soumd
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Was there a potential—>kinetic + soumd
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a
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whitecarrotcake\" post_id=\"1938910\" time=\"1569902437\" user_id=\"114080:
Gravity is unless he's lifting the sofa. The qn is pushing sofa, so it's frictional force.[/quote]Just adding on... as the mass of the sofa increases (because of the girl sitting on it) the friction between the sofa and the floor increases, so Its harder for the boy to push it.
if DD rmember correctly, its not friction. its due to gravity..quixation\" post_id=\"1938899\" time=\"1569901776\" user_id=\"480:
[quote=whitecarrotcake post_id=1938888 time=1569900796 user_id=114080]
Friction between sofa and floor
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