Topic: System of Masses
Concepts: Conservation of energy, Conservation of linear momentum

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Solution:

When the block reaches its maximum height, it is at rest with respect to the incline. Thus, they both have the same velocity $v$. Conserving linear momentum,

To find the height $h$, we conserve energy,

so the answer is C.

Topic: System of Masses
Concepts: 1D elastic collision, Speed vs. velocity

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Solution:

After the block leaves the inclined plane, the system is equivalent to an elastic collision (since energy and momentum are both conserved). The velocity of the block is given by the elastic collision equation,

The speed is the magnitude of the velocity,

so the answer is E.