while snowboarding mr. brooks (100 kg) takes a chair lift up to 800 m to the top of the mountain. if he snowboards down the mountain without stopping of falling, how fast will he be going when he get back to the bottom of the mountain

Given that,

Mass of Mr. Brooks = 100 kg

A chair lift up to 800 m to the top of the mountain.

To find,

How fast will he be going when he get back to the bottom of the mountain.

Solution,

Let v is the speed when he get back to the bottom of the mountain. Using the conservation of energy to find it.

So, the required speed is 125.21 m/s.

d

explanation:

v=uf/(u-f)

= 5.10/(5-10) convex lens has positive focal length

=50/-5

=-10 cm (formed at other side)

3. dark matter

empty space could also be a simple vacuum