Asubstance that speeds up the rate of a chemical reaction is called
a. a catalyst.
b. a lipid.
c. a molecule.
d. an element.

1. jay fills a wagon with sand (about 20 kg) and pulls it with a rope 30 m along the beach. he holds the rope 25° above the horizontal. the rope exerts a 20-n tension force on the wagon. how much work does the rope do on the wagon?

Most short-period comets do not have randomly oriented orbits because

1kg of water needs to recieve 4200j of energy to go from 90 degrees to 91 degrees. what is the specific heat capacity of water? what are the units?