Solution: Let the taxiing speed be V and the blocking speed be V. According to the conservation of energy, there are:

mgh= 1/2mv^2+ 1/2mv^2…… 1

According to the conservation of momentum, there are:

MV = mv

It can be obtained in two ways:

[1], V= 2m 2gh/m (m+m) under the radical sign.

[2]、e=-m^2gh/(m+m]

The slider does negative work on the block.