Confused about energy!
A physics lecture theatre is situated 3m east and 4m above reception. Calculate the minimum energy a 60kg receptionist would have to expend to reach the lecture theatre.
A 1800J
B 2400J
C 3000J
D 4200J
the answer is b due to mgh but why doesn't kinetic energy come into it to move 3m east?
A 1800J
B 2400J
C 3000J
D 4200J
the answer is b due to mgh but why doesn't kinetic energy come into it to move 3m east?
Original post by runny4
A physics lecture theatre is situated 3m east and 4m above reception. Calculate the minimum energy a 60kg receptionist would have to expend to reach the lecture theatre.
A 1800J
B 2400J
C 3000J
D 4200J
the answer is b due to mgh but why doesn't kinetic energy come into it to move 3m east?
A 1800J
B 2400J
C 3000J
D 4200J
the answer is b due to mgh but why doesn't kinetic energy come into it to move 3m east?
What's the minimum kinetic energy at the end?
Original post by runny4
A physics lecture theatre is situated 3m east and 4m above reception. Calculate the minimum energy a 60kg receptionist would have to expend to reach the lecture theatre.
A 1800J
B 2400J
C 3000J
D 4200J
the answer is b due to mgh but why doesn't kinetic energy come into it to move 3m east?
A 1800J
B 2400J
C 3000J
D 4200J
the answer is b due to mgh but why doesn't kinetic energy come into it to move 3m east?
Hello,
In this question, one should only consider the change in GPE. This is the minimum required energy to move 4m in the vertical direction. As for the horizontal direction, we do not know the minimum force required by the receptionist and therefore cannot calculate the work done in that respect (E = Fd). We therefore assume that the force required is negligible (horizontally) and so there is a 0J contribution from the horizontal motion. I hope that this has helped.
(edited 8 years ago)
Original post by Smithenator5000
Hello,
In this question, one should only consider the change in GPE. This is the minimum required energy to move 4m in the vertical direction. As for the horizontal direction, we do not know the minimum force required by the receptionist and therefore cannot calculate the work done in that respect (E = Fd). We therefore assume that the force required is negligible (horizontally) and so there is a 0J contribution from the horizontal motion. I hope that this has helped.
In this question, one should only consider the change in GPE. This is the minimum required energy to move 4m in the vertical direction. As for the horizontal direction, we do not know the minimum force required by the receptionist and therefore cannot calculate the work done in that respect (E = Fd). We therefore assume that the force required is negligible (horizontally) and so there is a 0J contribution from the horizontal motion. I hope that this has helped.
ok thanks
Original post by runny4
ok thanks
You're welcome.
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