please can someone help me. Most roller coasters begin with a large hill where the roller coaster train is lifted up the hill using a motor, such as from O to 2 on this diagram of the Goliath. The motor is designed to always move the roller coaster train with the same velocity. At the top of the hill, the roller coaster train continues moving, with no further input of energy.

Which of the following would have less momentum than a 52 kg cheetah running at 10 m/s?

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)

State one important difference between a physical change and a chemical change?