Ineed to know the answer and how to work it out

In which of the following cases is work being done on an object? question 2 options: pushing against a locked door carrying a box down a corridor pulling a trailer up a hill suspending a heavy weight with a strong

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

A0.580-kg rock is tied to the end of a string and is swung in a circle with a radius of 0.500 meters. the velocity of the rock is 4.50 m/s. what is the centripetal force acting on the rock? 15.5 n 5.22 n 69.8 n 23.5 n