How does a jack make changing a tire easier? a. a smaller force is applied by the hand over a shorter distance, exerting a greater force on the car through a greater distance. b. a smaller force is applied by the hand over a greater distance, exerting a greater force on the car through a shorter distance. c. a greater force is applied by the hand over a shorter distance, exerting a smaller force on the car through a greater distance.

The answer is B. A machine is anything that makes a force bigger in science. So a jack is a machine. All machines has one thing in common: when you put a force to them, they rise its size and apply a greater force somewhere else. For example, using a knife, you can't cut meat with your hand alone, but if you push down on a knife, the long handle and the sharpened blade enlarge the force you apply with your hand—and the meat slices naturally.

fgravity=10x10=100n case 1

fgravity=30x20=600n case 2

6 times more