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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: Boots on March 27, 2011, 03:14:19 pm

Title: help force Q
Post by: Boots on March 27, 2011, 03:14:19 pm

hey guys this is a first yr uni physics q
its pretty basic but i havent done physics in yr12 so i cant do it, if u cld help that wld be great

a cyclist rides up a steady slope for a distance of 1200m and rises 90m vertically as a result. the total mass of rider + cycle is 80kg
a) assume a drag force of 10N opposing the motion(due to air resistance and friction), what Total Work must be output by the rider for this climb?

Title: Re: help force Q
Post by: enpassant on March 27, 2011, 03:41:08 pm

10x1200 + 80x9.8x90 J

Title: Re: help force Q
Post by: soopertaco on March 27, 2011, 05:56:39 pm

Quote from: enpassant on March 27, 2011, 03:41:08 pm

10x1200 + 80x9.8x90 J

change in energy is equivalent to Work. So since there is a change in vertical height we can say that there is a change in gravitational potential energy: Mass * gravity * height

another formula for work is Force by distance thus: 10N * 1200m
add these to get there total

haha just thought i might add an explanation :)

Title: Re: help force Q
Post by: schnappy on March 27, 2011, 09:05:01 pm

Work = [Work done against gravity] + [Work done against friction]
Work = [80*90g] + [10*1200]
Work = bleh

Title: Re: help force Q
Post by: Boots on March 27, 2011, 09:53:21 pm

Quote from: soopertaco on March 27, 2011, 05:56:39 pm

Quote from: enpassant on March 27, 2011, 03:41:08 pm

10x1200 + 80x9.8x90 J

change in energy is equivalent to Work. So since there is a change in vertical height we can say that there is a change in gravitational potential energy: Mass * gravity * height

another formula for work is Force by distance thus: 10N * 1200m
add these to get there total

haha just thought i might add an explanation :)

Thank you soo much I really appreciate it