Ch. 13Lesson 2What are forces?

force•push

•pullpush

pull

force•measured in

newtons

gravity•Earth’s gravity pulls other objects toward its center

weight•amount of gravitational pull on every other object

pendulum•swings b/c of gravity

magnetism•force that pushes & pulls on other objects made of iron, nickel & cobalt

iron, nickel, cobalt

AGNETS, INC.

strongest force of attraction

friction•force when 2 materials rub against each other

friction•slows down motion of an object

work•energy used when a force moves an object

work•not done when the position of an object does not change

When work is doneActivity Work

Thinking about a math problem

Turning a jump rope

Holding a puppy

Lifting a puppy

Pulling on a locked door

Opening an unlocked door

Trying to scoop rock-hard ice cream

force X distance = work