Answer: 91.94 kg
Explanation: Supoose Al's mass is m. The combined mass is 168kg, so Jo's mass is 168 - m.
The Law of Conservation of Momentum states that when two objects collide, the total momentum of both objects before the collision is the same as the total momentum of both objects after the collision.
At the beginning, Al and Jo are united without movement, so their initial momentum is zero.
After the release of their hands, Al goes in one direction and Jo moves to the opposite direction. Suppose the direction Al is moving is positive. Conservation of momentum will be

where
index i referes to initial momentum
index f to final momentum
index 1 refers to Al
index 2 to Jo
Calculating:
![m(0.91)-[(168-m)(1.1)]=0](https://tex.z-dn.net/?f=m%280.91%29-%5B%28168-m%29%281.1%29%5D%3D0)


m = 91.94
Al has a mass of 91.94 kg.
<span>Answer: Height of the tree = 29.44m
Explanation:
The Sun is 30 degrees above the horizon, and the shadow of a tree it makes is 51 meters long. The right angled triangle can be constructed, where the base of the triangle is actually the shadow of the tree (which is 51m long) and the perpendicular of a triangle is the height of the tree. By using trignometric equation:
tan(</span>Ф<span>) = perpendicular/base
tan(30) = height-of-a-tree/51
height-of-a-tree = tan(30) * 51
height-of-a-tree = 29.44m</span>