The response of an object to the gravity is called

What kind of simple machine is a catapult?

How does a circuit breaker protect a refrigerator? a. when the current is too high, a metal strip in the fuse melts and opens the circuit. b. when the resistance is too high , a re-settable which opens a circuit c. when the current is too high , a re-settable switch opens the circuit d. when the resistance is too high a metal strip in the fuse melts and opens the circuit

Ascientist wants to test ways to reduce pollution in lake . what is the bestway of doing this