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    Hi, I have a homework question as follows:

    A smooth slope is inclined at tan^{-1} \frac {3}{4} to the horizontal. A body of mass 4kg is released from rest at the top of the slope and reachers the bottom with speed 7 m/s. Find the length of the slope.

    This is meant to be done using energy and work done.

    I am not entirely sure about all the forces here. Will the tractive force T include the 4g\sin \alpha or be as well as it? Am I on the right track?

    Many thanks in advance
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    1. Find the resultant of the forces along the plane. Smooth, no friction, so the resultant is simply a component of weight.
    2. Use F=ma to find acceleration.
    3. Use uvast to calculate the distance.
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    Or if you use energy and work done (didn't read your post fully) then it would be KE=GPE to get a vertical height. That and the angle is enough to work out the hypotenuse.
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    (Original post by bendent1234)
    Hi, I have a homework question as follows:

    A smooth slope is inclined at tan^{-1} \frac {3}{4} to the horizontal. A body of mass 4kg is released from rest at the top of the slope and reachers the bottom with speed 7 m/s. Find the length of the slope.

    This is meant to be done using energy and work done.

    I am not entirely sure about all the forces here. Will the tractive force T include the 4g\sin \alpha or be as well as it? Am I on the right track?

    Many thanks in advance
    Since it's a smooth slope you have GPE Lost = KE Gained.

    And they're the only two things you need to worry about. You don't need to work out the component of weight down the slope - energy takes care of all that for you.
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    Thanks
 
 
 
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