Which is a characteristic of a physical change?

the chemical bonds in the substance are unchanged.
the change cannot be seen.
the molecules all move at the same speed.
the substance has reacted with another substance.

Which situation will have the highest resistance? a. long wire and high temperatureb. short wire and high temperaturec. long wire and cold temperaturedshort wire and low temperature

Question part points submissions used suppose that 2 j of work is needed to stretch a spring from its natural length of 26 cm to a length of 36 cm. (a) how much work is needed to stretch the spring from 28 cm to 32 cm? (round your answer to two decimal places.)

What kind of simple machine is a catapult?