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# Machanics M1 Question watch

1. Hey, i have tried to do this question a few times and can't do it. I was wondering if somebody could help.

A boy is tobogganing down a slope cinlined at 25deg to the horizontal. The resistance to his motion amount to 15N. By modelling the boy and his toboggan as a single particle, find the mass of the boy and his toboggan when his acceleration is 3.9 m.s-1 ?

I would appriate working as i already know the answer from the book (62.1 kg). I can then work though it and see what you did and try a similar question.

Thanks bob
2. Draw a diagram.
Label all the forces, and components of forces parallel and perpendicular to the slope.
Label the angles too.

Fresultant = ma, down the slope.
3. drawing the diagram helps but anyway let W= weight .9.8Wcos65 - 15 =3.9W becaue F-R=Ma. Dividing accross by 9.8 u get Wcos65 - 15/9.8=3.9/9.8W. solve cos 65 you get 0.4226N -3.9/9.8N = 15/9.8 so 0.24639W=15/9.8 W. W =62.1Kg. Hope that helps
4. Thanks, yeh i did draw a diagram but just couldn't get my head around it.

I'll write it down and go though it thanks (this wasn't homework just trying to get better at resolving)

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