Acompound machine is sued to lift a car. if you apply a force of 60 n to the machine, it lifts the car with a force of 550 n.

a. what is the mechanical advantage of the machine?

b. the machine has an efficiency of 35%. if you perform 1150 j of work, how much useful work does the machine do?

I'm thinking it's 2 you are asked to explain the earth's magnetic field. which is the best reply? 1. the earth's magnetic south is similar to the north pole of a magnet. 2. the earth's core has a strong magnetic charge similar to the south pole of a magnet. 3. the earth's geomagnetic south is similar to the south pole of a magnet. 4. the earth's magnetic charge is not centered at either pole; it varies based on location.

Which of these is constant for all types of electromagnetic radiation in a vacuum? select one: a. wavelength b. frequency c. photon energy d. amplitude e. velocity

Why do atoms emit energy of only specific wavelengths