Final answer:
The microwave oven, invented in 1946 from World War II radar technology, significantly altered food preparation by using radiation to heat food quickly, impacting the work of professional groomers and home cooks.
Step-by-step explanation:
The invention in the 1940s that helped change how groomers work is the microwave oven. This invention, developed from World War II radar technology in 1946, revolutionized food preparation in homes and businesses alike.
As opposed to traditional cooking methods, the microwave oven used radiation to heat food quickly and efficiently, simplifying and speeding up the process for both professional groomers in a salon setting and for individuals at home.
The introduction of the microwave oven is just one example of how advancements in technology can have a significant impact on daily life and work processes.