When an unstoppable force meets an immovable object

Ais not a compound machine. a. bolt b. shovel c. handcart (dolly) d. see-saw (teeter totter)

When an object is heated it contracts. a. true b. false

There are two-speed cameras, one in an are where the speed limit is 30 km/h and another where the speed limit is 50 km/h. in which will there be a smaller time interval between the photographs? explain your answer.