M2 Maths (help needed) - Question using Energy, Gpe, Ke, etc
A station escalator raises passengers a height of 15 metres, moving at 4 m/s up the slope.
1) A passenger of mass 75 kg steps on the escalator (with zero velocity). How much energy does the escalator mechanism expend in taking her to the top and delivering her at a speed of 4 m/s.
2) In the rush hour 200 passengers per minute, of average mass 75 kg, use the escalator. At what power must the motor work to cope with this demand?
1) A passenger of mass 75 kg steps on the escalator (with zero velocity). How much energy does the escalator mechanism expend in taking her to the top and delivering her at a speed of 4 m/s.
2) In the rush hour 200 passengers per minute, of average mass 75 kg, use the escalator. At what power must the motor work to cope with this demand?
Original post by TheJ0ker
For the first one do use W = F x D
1)
F = 75 * 9.8
W = FD
W = (75 * 9.8) * 15 = 11025
= 11025 J ?
where does the 4m/s come into it?
2)
help?
Original post by Logan234
1)
F = 75 * 9.8
W = FD
W = (75 * 9.8) * 15 = 11025
= 11025 J ?
where does the 4m/s come into it?
2)
help?
F = 75 * 9.8
W = FD
W = (75 * 9.8) * 15 = 11025
= 11025 J ?
where does the 4m/s come into it?
2)
help?
I think the 4m/s is a bit irrelevant in the first bit, and I'm learning this topic at the moment and haven't learnt about power yet
so I'm not much help for part 2.
Original post by iluvmaths
power= force apllied x velocity
p= 75g x 4
p= 75g x 4
so for 200 people over a minute = 3.3 people per second = 250 kg per second = 2450 N per second => power = 2450 x 4 = 9.8kw?
right?
Original post by TenOfThem
Power is the rate of change of work
So you will use the speed to find the time taken
So you will use the speed to find the time taken
^^^^ is that right? ( what I posted above )
Original post by iluvmaths
is this the right answer from ur booklet?
the answer is not given :/ but it is only 2 marks, so that looks about right for the working needed...
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