Ultrasonic waves have many applications in technology and medicine. one advantage is that large intensities can be used without danger to the ear. what is another advantage of their short wavelength? (why do microscopes use blue light rather than white light to see detail? ) 1. the short wavelengths of ultrasonic waves allow the imaging of smaller objects. 2. it is easy to cook food with ultrasonic waves. 3. ultrasonic waves are good for our health. 4. ultrasonic waves are easy to diffract.

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.

Aweight lifter raises a 1600 n barbell to a height of 2.0 meters. how much work was done? w = fd a) 30 joules b) 3000 joules c) 320 joules d) 3200 joules

What component of earth’s atmosphere exists entirely as a result of photosynthesis?