Which example describes a scientist using a model to represent a system or structure in our universe? O Colored foam balls are used to show where the planets are located in our Solar System
A microscope is used to magnify the parts of a plant cell
A test tube is used to mix two chemicals together
A stopwatch is used to time a falling object before it hits the ground

Acoal-fired plant generates 600 mw of electric power. the plant uses 4.8 x 10^6 kg of coal each day, and the heat of combustion of coal is 3.3x 10^7 j/kg. the steam that drives the turbines is at a temperature of 300° c, and the exhaust water is at 37° c. (a) what is the overall efficiency of the plant for generating electric power? (b) how much thermal energy is exhausted each day? (c) what is the change in entropy of the universe for this heat engine? (d) using the same heat reservoirs, what is the maximum possible (carnot) efficiency for a heat engine?

The earth exerts a gravitational force of 500 n on amy. what is amy’s mass in kg?

Which of the the following are examples of projectile motion of both projectile motion and two dimensional motion