according to the author, what effect do the cart's wheels have on most roller coasters?
a)
the wheels cause friction.
the wheels eliminate friction.
the wheels give the cart kinetic energy.
the wheels give the cart potential energy.

The Cartwheels cause friction.

Option A.

Explanation :

The cart on the roller coaster works on the principle of conservation of energy which says that the energy is only transformed from one form to another. It is not lost.

When the cart with wheels on the roller coaster goes up, the gravitational potential energy increases with height and is the highest at the highest point on the roller coaster. As the cart comes down, the potential energy is converted into kinetic energy. The kinetic energy is the highest at the bottom of the coaster.  

Friction is offered by air and the wheels. That is why the roller coaster will not go on forever unless it provided some external energy.  

a,b,d are the three sentences that use a reflexive pronoun

the answer is actually c   i just got done with the test.