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# M2 Work, energy and power help, question included. Watch

1. A girl and her sledge have a mass of 40kg. She starts from rest and descends a slope which is incline at 25 degrees to the horizontal. At the bottom of the slope the ground becomes horizontal for 15 meters before rising at 6 degrees to the horizontal. The girl travels 25 meters up the slope before coming to rest once more. There is a constant resistance to motion of magnitude 18 Newtons. Calculate the distance the girl travels down the slope.

The answer is 11.8 meters. But i am lost as to how to get there.

You have to use the conservation of mechanical energy and the work energy principle.
2. (Original post by UsamaS)
A girl and her sledge have a mass of 40kg. She starts from rest and descends a slope which is incline at 25 degrees to the horizontal. At the bottom of the slope the ground becomes horizontal for 15 meters before rising at 6 degrees to the horizontal. The girl travels 25 meters up the slope before coming to rest once more. There is a constant resistance to motion of magnitude 18 Newtons. Calculate the distance the girl travels down the slope.

The answer is 11.8 meters. But i am lost as to how to get there.

You have to use the conservation of mechanical energy and the work energy principle.
So mgh = Fd

3. (Original post by UsamaS)
A girl and her sledge have a mass of 40kg. She starts from rest and descends a slope which is incline at 25 degrees to the horizontal. At the bottom of the slope the ground becomes horizontal for 15 meters before rising at 6 degrees to the horizontal. The girl travels 25 meters up the slope before coming to rest once more. There is a constant resistance to motion of magnitude 18 Newtons. Calculate the distance the girl travels down the slope.

The answer is 11.8 meters. But i am lost as to how to get there.

You have to use the conservation of mechanical energy and the work energy principle.
You'll only help yourself (a lot!) if you draw a diagram and label it thoroughly.

Once you've done that, recall the principles of energy and WD from the textbook/your notes.
4. (Original post by Mr M)
So mgh = Fd

You are awesome thank you so much, so annoyed that i did not see that
5. (Original post by UsamaS)
You are awesome thank you so much, so annoyed that i did not see that
Ok good.

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