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primary 6 | Science
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Yap Cheng An
Yap Cheng An

primary 6 chevron_right Science chevron_right Singapore

If possible, it will definitely make my day if you can help me overcome the difficulty of this question [ Part (c) only]. Please provide an explanation as well. I am looking forward to learn something new from you. Thank you!

Date Posted: 4 years ago
Views: 587
snell
Snell
4 years ago
(c)
when a falling object lands on the helmet, a dent would be made in the helmet. Energy of the falling object would be dissipated by the helmet.

This reduces any energy left of the object to a minimum and thus prevent any injuries to the head.


...
Yap Cheng An
Yap Cheng An
4 years ago
May I know what is the meaning of dissipated?
Yap Cheng An
Yap Cheng An
4 years ago
Sorry to interrupt, but I do want to know if we need to include the conversion of energy? For example, in this case, kinetic energy of the falling object converted to heat and sound energy when it came into contact with the helmet.
snell
Snell
4 years ago
dissipate:
1. disperse
2. fritter away
3. spread out
snell
Snell
4 years ago
this depends on ur teacher's expectation
it is a 1 mark qn

it is gd to hv.
But during exam, u hv to take note of the time allowed.

so keep the conversion thingy to a minimum

gravitational potential energy of falling object to kinetic energy (before impact) to thermal energy and sound energy upon impact with helmet.
Yap Cheng An
Yap Cheng An
4 years ago
However, I have an answer to this question [ Part (c) ] in my mind: As the object is falling, it possesses kinetic energy. The helmet is hard enough to overcome the pushing force of the object as the object tries to push itself against the surface of the helmet. Hence, in the worst possible case, only an unharmful dent would be created on the helmet and the worker is safe from injuries.
snell
Snell
4 years ago
erhmm, ...
may i know whats ur ans for (b) ?

u shld know that (c) is related to (a) & (b).

1. u r not relating the "pushing force" to "kinetic energy".
force & energy r two different quantities

2. u r not relating "hard enough" to "pushing force".
hardness & force r two different quantities

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Yap Cheng An
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