Speed Sliding down a hill (frictionless)

AI Thread Summary
To calculate the speed of a child and sled sliding down a frictionless hill, one can use two methods. The first involves calculating the gravitational force, determining its component along the hill, and applying accelerated motion formulas to find the final speed. The second method equates the potential energy at the top of the hill with the kinetic energy at the bottom, allowing for a straightforward calculation. Both approaches will yield the same result for the speed at the bottom of the hill. Understanding these principles is essential for solving similar physics problems.
Bigdane
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A child and sled with a combined mass of 53.8 kg slide down a frictionless hill that is 8.56 m high. If the sled starts from rest, what is its speed at the bottom of the hill?

m/sim not sure how to calculate speed given the information.
help please?
 
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There are two ways to tackle this problem. One is to work with the force of gravity downward, find the component of that along the hill, and then the acceleration that it causes. Accelerated motion formulas will allow you to work out the final speed after sliding the length of the hill.

The other approach is to say that the potential energy at the top is equal to the kinetic energy at the bottom. Set the two formulas equal, put in numbers and out pops the answer!
 
thanks a bunch!
 

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