What is the difference between chemical change and a physical change?

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force

Auniform solid cylinder with a radius of 10 cm and a mass of 3.0 kg is rotating about its center with an angular speed of 33.4 rpm. what is its kinetic energy?

Pressure is a measure of force per unit area or p=f/ap=f/a. a student is checking the amount of pressure their car exerts upon the road. the car weighs 22 tons ( us short ton ). the student finds the dimensions of each tire's footprint on the road is 12.5 cm x 16.5 cm. in pounds per square inch (psi), what is the total pressure the car exerts upon the road?