james_rich
Nov22-04, 06:20 PM
Hey just gettin a bit stuck on this question.....i'll attempt to answer it, but it really doesn't look right to me.
A cable car is used to carry people up a mountain. The mass of the car is 2000kg and it carries 80 people, of average mass 60kg. The vertical height travelled is 900m and the time taken is 5 minutes.
i) Calculate the gain in GPE of the 80 people in the car
GPE = mg/\ h
= (80 x 60) x 9.81 x 900
= 4.2 x 10^7 J
Is this right so far? :confused:
ii) Calculate the minimum power required by a motor to lift the cable car and its passengers to the top of the mountain.
Power = Work Done/Time Taken
Work Done = Force x Distance = (4800 + 2000) x 9.81 x 900
= 6.0 x 10^7
Power = (6.0 x 10^7) / 300 (as 5 mins = 300s)
P = 2.0 X 10^5 watts
These are the answers I got........i think i've used the right method, just need some reassurance!
Thanx in advance!
A cable car is used to carry people up a mountain. The mass of the car is 2000kg and it carries 80 people, of average mass 60kg. The vertical height travelled is 900m and the time taken is 5 minutes.
i) Calculate the gain in GPE of the 80 people in the car
GPE = mg/\ h
= (80 x 60) x 9.81 x 900
= 4.2 x 10^7 J
Is this right so far? :confused:
ii) Calculate the minimum power required by a motor to lift the cable car and its passengers to the top of the mountain.
Power = Work Done/Time Taken
Work Done = Force x Distance = (4800 + 2000) x 9.81 x 900
= 6.0 x 10^7
Power = (6.0 x 10^7) / 300 (as 5 mins = 300s)
P = 2.0 X 10^5 watts
These are the answers I got........i think i've used the right method, just need some reassurance!
Thanx in advance!