It's real name is "WEIGHT TRANSFER MACHINE". But, more commonly known as a "SLED".
A tack is a type of wedge, which is a simple machine that is used to push things apart or hold things together.
The force that pulls things forward is called "thrust."
It depends on what kind your talking about because they can al sorts of things.
a window is a froggy
candy bars, crackers, chips, juice
pushes and pulls are things you do when energy is applied
This is called a Bailer
well it is a lever bacause a lever is used to adjust things
agonists
Gravitational force (or gravity) is a force that pulls things together.
wedge is another simple machine kind of lever